Completeness
Finds what is missing or extra compared with the reference.
OutputOmission and commission rates by area or feature type
Mapping that holds up at any scale.
We help private and public organizations build better maps and datasets, strengthen QA/QC, set best practices, create custom metrics, validate spatial data and use AI safely, backed by over a decade of big tech map making.
Illustrative terrain
Our goal is simple: spatial data that your organization can trust and act on. We work with private and public teams of any size, from a single map to a large-scale product.
Experienced GIS support when you need a clear answer, a better workflow or more capacity on a project.
View geospatial consultingSpatial pipelines, databases, automation and AI-assisted mapping.
View detailsStrategy, data, design and build support for large-scale map products.
View detailsCustom datasets, QA/QC databases, automated checks and quality review.
View detailsCustom metric suites, reviews of your existing metrics and best-practice implementation.
View detailsIndependent testing of spatial data and AI output, plus ground truth datasets.
View detailsTraining, safe-use rules and best practices for any industry, with a focus on local government.
View detailsOver a decade of building maps in big tech, across base map data, design, imagery and quality.
We use AI where it helps, then test the results against reference data before you rely on them.
We can work with the tools you already use, commercial or open source, or recommend what fits your project and budget.
You receive the outputs, the method and the files, so you are not left depending on us.
We work with teams of any size and industry, and these are the groups we focus on.
Geospatial depth for product and engineering teams building with maps and location data.
For tech companiesSite and corridor mapping, terrain analysis and combined survey, CAD and GIS data.
For engineering and construction firmsWatershed, wetland and land cover mapping, with data you can trace and maintain.
For conservation authoritiesAsset and land use data, open data publishing, public web maps and GIS reviews.
For Ontario municipalitiesAI processes imagery and messy data in a fraction of the time. Every result is then checked against reference data, so you get the speed without losing confidence in the map.
See how we work View our sample workStart small or commit to something longer. We shape the work around what you need.
An agreed deliverable, timeline and price. Best when you know what you need.
A set amount of support each month. Best for continuing updates and maintenance.
We work inside your team for a period. Best when you need capacity and expertise.
A short, paid assessment with clear recommendations. A low-risk way to start.
From a single map to a national dataset, we shape the work around what you need. We can support your team for a few days, lead a project from start to finish, or build a large-scale mapping product with you.
Spatial analysis, cartography, GIS strategy and hands-on support.
View detailsSpatial pipelines, databases, automation and AI-assisted mapping.
View detailsStrategy, data, design and build support for large-scale map products.
View detailsCustom datasets, QA/QC databases, automated checks and quality review.
View detailsCustom metric suites, reviews of your existing metrics and best-practice implementation.
View detailsIndependent testing of spatial data and AI output, plus ground truth datasets.
View detailsPractical support for any industry, with a special focus on local governments and municipalities.
View AI training and safetyAn agreed deliverable, timeline and price. Best when you know what you need.
A set amount of support each month. Best for continuing updates and maintenance.
We work inside your team for a period. Best when you need capacity and expertise.
A short, paid assessment with clear recommendations. A low-risk way to start.
We are not tied to any one platform. We can work with the tools you already use, or recommend and build with what fits best, whether commercial or open source.
These are examples, not limits. If your team uses something else, we can work with it.
Experienced GIS support when you need a clear answer, a better workflow or more capacity on a project.
Thematic maps turn tables into patterns people can act on. This one compares mapped stream length per square kilometre across the four units.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
Reliable systems for moving, processing and improving spatial data, with AI used where it can be measured and checked.
A repeatable pipeline keeps people and AI in the right places, and it can run again whenever the data changes.
Support for teams building maps and location features into products, drawing on over a decade of large-scale map making.
The same part of the Humber River watershed is drawn for three different audiences.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
Spatial data built to your specification, and the systems to prove that it is right.
Try our QA/QC database sample or see our validation and ground truth service.
Showing issues on a map reveals patterns that a list can hide. These 20 candidates still need review by a person.
Review them in our QA/QC sample
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
A suite of metrics built around your needs, or a clear review of the ones you already use, so you can see data quality and act on it.
A useful metric shows where to act. East Humber has the highest share of stream length with an official name, and Bolton Dam has the lowest. See more in our Humber River dashboard.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
Every suite is tailored to your work. Common starting points include the measures below, and you can see real examples in our Humber River sample.
Finds what is missing or extra compared with the reference.
OutputOmission and commission rates by area or feature type
Measures how far features sit from their true location.
OutputRMSE, offset direction and error maps
Checks geometry, topology and schema against the rules.
OutputRule pass rates, gaps, overlaps and invalid records
Tests whether classes, names and attributes are right.
OutputConfusion matrix and accuracy by class
Shows how current data is, and how quickly changes arrive.
OutputAge by region, update lag and freshness trend
Shows where quality or detail changes across an area.
OutputGrid scores, regional rankings and heat maps
Compares AI or vendor output with ground truth.
OutputPrecision, recall, F1 score and error examples
Tracks whether quality work is making progress.
OutputOpen issues, time to fix and sign-off rate
These are illustrations of how each metric works, not measured results. We tailor every suite to your data and goals, and can align it with quality elements from ISO 19157-1.
Practical support to help your organization use AI safely and well. We work across industries, with a special focus on local governments and municipalities.
Why it matters for public bodies. In January 2026, Ontario's Information and Privacy Commissioner and Human Rights Commission released six joint principles for responsible AI in the public sector. They are recommendations, not legal requirements, but they offer a useful starting point. Some municipalities, such as Norfolk County, have already adopted AI policies.
Start where you are. Each step can stand alone or build on the last.
These are the six principles from the Ontario guidance, with what each can mean for your organization.
Test tools before use and keep checking that they work as intended.
Monitor for harm, protect against security threats and retire unsafe systems.
Limit the data used and build privacy in from the start.
Look for bias and correct discriminatory results.
Document where AI is used and tell people when they interact with it.
Name who is responsible, keep people in charge and make it possible to pause a system.
AI support is not limited to geospatial work, but this is where our experience runs deepest. We can help you evaluate AI-assisted mapping, prepare spatial training data and test results against ground truth.
These are examples of work we can take on, not past client projects.
Map current use, risks and quick wins across your organization.
Run a practical session built around your real tasks and rules.
Create a clear starting policy for your legal and privacy teams to review.
We do not provide legal advice. Please confirm legal and privacy requirements with your own counsel.
We test spatial data and AI output against trusted reference data, and build ground truth datasets others can measure against.
Every result can be traced to a specification, a sample and a documented method.
A second set of eyes on data you build, buy or depend on.
Reference data with known quality that others can test against, built from open datasets, high-accuracy sources and field verification when necessary.
We choose measures to match your data and how it will be used.
Compares AI or vendor output with ground truth.
OutputPrecision, recall, F1 score and error examples
Measures how far features sit from their true location.
OutputRMSE, offset direction and error maps
Finds what is missing or extra compared with the reference.
OutputOmission and commission rates by area or feature type
These are illustrations of how each metric works, not measured results.
We match each source to the accuracy your project needs, and go to the field only when necessary.
Open or authoritative does not automatically mean accurate enough, so we assess each source for the test at hand.
Reference records keep their source, date, method and known accuracy.
We confirm how each source may be used and shared, and credit it as required.
A validation is only useful if people can trust how it was done.
Checkpoints should come from an independent source of higher accuracy than the data being tested.
Data used to train a model is kept out of the data used to test it.
We disclose any involvement with the data, and do not validate our own work as independent.
No reference is perfect, so we document how ground truth was made and its known limits.
These are examples of work we can take on, not past client projects.
Test a sample of a dataset before you commit to buying it.
Build a reference set and score AI output against it.
Compare two or more providers against the same reference data.
See our dataset validation sample See how we track issues
Our validations are independent professional assessments. They are not legal surveys or regulatory certifications.
The data and the rules change from one industry to the next. The discipline of good mapping does not.
Conservation authorities and environmental teams depend on data that is current, traceable and easy to explain to regulators and communities.
Engineering and construction projects bring together survey, design and GIS data that often use different formats and coordinate systems.
Ontario municipalities and other public organizations need accurate, accessible data that can be maintained long after a project ends.
Product and engineering teams need geospatial depth without slowing down their release cycle.
If your data has a location, the same methods usually apply. Tell us what you are trying to decide.
We do not provide legal land surveys or stamped engineering. We work alongside your licensed professionals.
Geospatial expertise for teams building with maps, location data and spatial AI, without slowing your release cycle.
A repeatable pipeline keeps people and AI in the right places, and it can run again whenever the data changes.
These are examples of work we can take on, not past client projects.
Compare open and licensed sources on coverage, quality, cost and terms.
Measure your current data and set metrics to track between releases.
Test extracted features against reference data before you ship them.
Reliable GIS support for project teams that need survey, design and spatial data to work together.
Project teams can see terrain and water together for early planning. Contours here are shown every 25 m.
Screening-level sample, not for design.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
We do not provide legal land surveys or stamped engineering. We work alongside your licensed surveyors and engineers.
These are examples of work we can take on, not past client projects.
Combine open and project data into one map of the constraints along a route.
Align and clean project files so that your teams work from one dataset.
Check datums, completeness and consistency before design decisions rely on the data.
See our Humber River sample Try our QA/QC database sample
Watershed mapping, data harmonization and QA/QC for teams responsible for Ontario's watersheds.
Preparing for consolidation. Ontario's 36 conservation authorities are set to amalgamate into 9 regional authorities on February 1, 2027. Merging organizations often means combining datasets built to different standards. We can help you take stock of your data, align it and check it.
A clear process helps merging organizations keep track of every dataset and decision.
Four official watershed units, with streams and waterbodies from the Ontario Hydro Network, covering 908.5 km².
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
These are examples of work we can take on, not past client projects.
Create a clear record of datasets, owners, formats, licences and known gaps.
Map how fields and categories in different datasets relate to a shared standard.
Combine authoritative data into a checked profile, like our Humber River sample.
See our Humber River sample Try our QA/QC database sample
Accurate, accessible spatial data that your staff can maintain long after a project ends.
Public maps work best when they show only what people need. This style keeps the main rivers and clear labels.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
These are examples of work we can take on, not past client projects.
Measure how complete and consistent your asset data is, then prioritize fixes.
Assess which datasets are ready to publish and what each one needs first.
Turn a priority dataset into a clear public map, tested for accessibility.
See our Humber River sample Try our QA/QC database sample
Our founder has spent over a decade building maps inside big tech. We know how product and engineering teams work, and we can step in without slowing yours down.
Turn location data into features your users can rely on.
Add geospatial depth to the systems you already run.
You are adding location to your product and need the plan, data and design right.
You need to compare data sources or decide whether to build, buy or combine.
Users are finding errors, and you need to measure and fix them at the source.
You need geospatial expertise on the team for a project or a period of growth.
We can join your planning, tools and review process rather than adding a separate one.
Decisions, methods and code stay clear for the people who take them forward.
We hand over the work and the knowledge so your team can carry it on.
AI processes imagery and messy data in a fraction of the time. Every result is then checked against reference data, so you get the speed without losing confidence in the map.
We can work with any tooling, commercial or open source, and recommend what fits your project and budget.
Agree on the decision the map supports and the accuracy it needs.
Audit sources, licences and reference systems, including NAD83(CSRS) and CGVD2013 for Canadian work.
Combine AI, code and GIS in a documented, repeatable workflow.
Test results against reference data. A person signs off, and you receive the outputs, method and files.
Quality means different things on different projects, so we agree on the measures that matter before work starts.
Are features in the right place for the way the data will be used?
Is anything missing, or included when it should not be?
Are names, classes and values correct?
Do geometry, topology and schema follow the rules?
Is the data recent enough, and is its age clear?
Can each result be traced to its source and method?
We test AI output against reference data and report the results.
A person reviews the results and signs off on what we deliver.
We confirm how your data will be handled, and we do not use it to train models unless you agree in writing.
We are a Canadian geospatial company based in the Greater Toronto Area. Our goal is to help private and public organizations turn data into decisions by strengthening their datasets, improving QA/QC and putting best practices in place. We bring over a decade of big tech map making, traditional GIS practice and modern AI to that work. Isarithm is a founder-led firm, and we bring in trusted specialists when a project needs them.
Isarithm is led by a founder with over a decade of experience building maps in big tech, supporting work at global scale. That experience is backed by a university education in geospatial studies and computer science.
Worked on consumer map products and global base map data, including roads, buildings, land use and places.
Worked on programs covering quality metrics, validation, QA/QC and ground truth.
Worked on imagery-based mapping and AI, including machine learning, feature extraction and training data.
Experience spans GIS and data work, data science and engineering, technical leadership, program management, and leading teams of 10 to 25 people.
What this means for you: senior experience from a founder who has seen what breaks at scale, applied at the size your project needs.
We show our methods and measure our results.
We explain spatial work in terms your team can use.
We recommend what fits, not what is newest or most expensive.
We leave you with work that your team can understand and maintain.
Our logo comes from a basic rule of map reading. Where a contour line crosses a stream, it bends into a V that points upstream. This is known as the rule of Vs.
It is a small example of what we care about: a few simple lines can tell you how the land works, if you know how to read them. The blue line is a nod to the water behind the rule.
We are not tied to any one platform. We can work with the tools you already use, or recommend and build with what fits best, whether commercial or open source.
These are examples, not limits. If your team uses something else, we can work with it.
A sample of how we turn open data into decisions: official Ontario datasets, combined into one watershed profile, measured with a metric suite and checked.
| Unit | Code | Area (km²) | Share | Streams (km) | Density (km/km²) | Lakes and ponds | Open water (ha) |
|---|
Waterbodies crossing a unit boundary are counted in each unit they touch. Elevations come from contours, so true highs and lows can differ.
This is the kind of metric suite we can build around your data. It measures 1,838.9 km of watercourse network in the Humber River watershed, including modelled flow paths.
9.8 km sits outside the main network, across 10 separate groups.
Required fields are filled on all 6,773 segments. 11.4% of stream length has an official name.
Share of network length with a last geometry update in 2019, the most common year.
Share of network length recorded as within 5 metres. This is the source’s stated value, not an independent test.
| Unit | Connected | Isolated (km) | Flow gaps | Required fields | Named streams | Within 5 m | Median update |
|---|---|---|---|---|---|---|---|
| Black Creek - Humber River Outlet | 98.8% | 6.2 | 1 | 100% | 12.6% | 99.8% | 2019 |
| West Humber River | 99.8% | 0.7 | 1 | 100% | 9.5% | 100.0% | 2019 |
| Bolton Dam - Humber River | 99.8% | 0.9 | 2 | 100% | 8.7% | 100.0% | 2019 |
| East Humber River | 99.5% | 2.0 | 2 | 100% | 15.1% | 100.0% | 2019 |
The highlighted unit has the lowest connectivity.
Network length by the year its geometry was last updated.
Black Creek - Humber River Outlet holds 6.2 of the 9.8 isolated kilometres, so we would review it first.
An update date shows when geometry was last edited, not whether it still matches the ground. A real project would compare it with recent imagery.
Independent accuracy testing needs reference data, such as survey points or LiDAR. We would add this for a client project.
Each graph answers a practical question. All of them are calculated from the official datasets used in this sample.
Grid metrics show variation hidden by unit totals. Across 247 cells, the median is 1.73 km/km² and the highest is 4.27 km/km². A low value can reflect the landscape or less detailed mapping, so unusual cells are good candidates for review.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project. Cells with under 25% of their area in the watershed are left out.
Stream length per square kilometre, by unit.
Network length by type. Modelled paths connect flow through features such as waterbodies.
Length outside the main connected network, by unit. These are candidates for review.
Range of contour elevations in each unit. True highs and lows can differ.
Mapped waterbody area as a share of each unit.
Count of clipped waterbody pieces by size. Small features are often the hardest to keep complete.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
The graphs above show part of what is possible. We can build a suite from any of these measures, or improve the metrics you already use.
Finds what is missing or extra compared with the reference.
OutputOmission and commission rates by area or feature type
Measures how far features sit from their true location.
OutputRMSE, offset direction and error maps
Checks geometry, topology and schema against the rules.
OutputRule pass rates, gaps, overlaps and invalid records
Tests whether classes, names and attributes are right.
OutputConfusion matrix and accuracy by class
Shows how current data is, and how quickly changes arrive.
OutputAge by region, update lag and freshness trend
Shows where quality or detail changes across an area.
OutputGrid scores, regional rankings and heat maps
Compares AI or vendor output with ground truth.
OutputPrecision, recall, F1 score and error examples
Tracks whether quality work is making progress.
OutputOpen issues, time to fix and sign-off rate
These are illustrations of how each metric works, not measured results. We tailor every suite to your data and goals, and can align it with quality elements from ISO 19157-1.
We ran these checks on the datasets used for this sample. Items marked Review would go to a person on a real project. You can review them yourself in our QA/QC database sample.
4 of 4 watershed units have valid geometry.
Units overlap by 0 m² and combine into one polygon with 0 holes.
Our equal-area calculation gives 908.48 km², matching the 908.48 km² in the source attributes.
We removed 2,989 repeated records from the paged download. Final counts match the source service: 10,781 watercourses, 5,494 waterbodies and 17,277 contours in the search area.
6,773 clipped watercourse segments checked. Blank permanency values: 0.
99.5% of the network connects as one system. 9.8 km across 10 separate groups does not. These may be real, or may result from clipping or gaps in the data. They are highlighted on the map.
6 segments are classed as flow gaps in the source. A person would confirm how these should be treated.
11.4% of stream length carries an official name. The rest would rely on other identifiers in reporting.
Ontario Watershed Boundaries, Ontario Hydro Network (Watercourse and Waterbody) and Contour, from Land Information Ontario, retrieved November 2026. Contains information licensed under the Open Government Licence – Ontario. Map geometry is simplified for display.
Find issues, review them, record each decision and show what was checked. Try the workflow below using issues from the Humber River data.
| Issue | Check | Severity | Unit | Size | Status |
|---|
Each issue links back to its dataset and the check that found it. Every change is kept as an event, so nothing is lost when a status changes.
CREATE TABLE issues (
issue_id text PRIMARY KEY,
dataset_id integer NOT NULL REFERENCES datasets (dataset_id),
check_id integer NOT NULL REFERENCES checks (check_id),
unit_code text NOT NULL,
severity text NOT NULL CHECK (severity IN ('High', 'Medium', 'Low')),
status text NOT NULL DEFAULT 'Open',
geom geometry(Point, 26917) NOT NULL,
created_at timestamptz NOT NULL DEFAULT now()
);
-- Issues still waiting for sign-off, by watershed unit and severity
SELECT unit_code, severity, count(*) AS waiting
FROM issues
WHERE status <> 'Signed off'
GROUP BY unit_code, severity
ORDER BY unit_code, severity;Issues, decisions and sign-offs sit in one place, not across spreadsheets and email.
The audit trail shows who decided what, when and why.
Counts and progress come directly from the records, so reports always match the data.
See how we approach real problems. These are samples we built to show our methods, not client projects, and each one states what is real and what is simulated.
Official Ontario data, profiled with an interactive map, dashboard and graphs.
View sampleReal open dataA dataset scored against reference data, with metrics and a field verification queue.
View sampleReal issues, practice workflowReview real issues, record decisions and keep an audit trail.
View sampleReal open dataA municipality's published water, sanitary and storm networks, with a detailed map, main break analysis and quality checks.
View sampleReal run on open dataA tested pipeline from public web service to published data, with lineage, data contracts, damage tests and reproducible results.
View sampleYour projectTell us what you need to check, and we can suggest a focused first project.
Contact usHow we test a dataset against reference data, score it against a requirement and decide where field verification is worth the trip.
Share of the test data found near the reference.
Share of the reference found near the test data.
A single score that balances precision and recall.
Typical distance from a test line to the nearest reference line.
The test data sits close to the reference, but about one-fifth of the reference network has no match within 50 m. It would not meet this example requirement for detailed network work, though it could still suit overview maps.
Precision stays near 100% while recall climbs with tolerance. That pattern points to missing detail rather than misplaced lines.
Results at five match distances.
Share of each unit's reference network matched within 50 m.
| Unit | Test data (km) | Precision | Recall | F1 score | Median offset |
|---|---|---|---|---|---|
| Black Creek - Humber River Outlet | 370.8 | 100.0% | 82.1% | 90.2 | 2.1 m |
| West Humber River | 335.7 | 100.0% | 84.6% | 91.7 | 2.1 m |
| Bolton Dam - Humber River | 299.7 | 100.0% | 74.4% | 85.3 | 2.1 m |
| East Humber River | 286.5 | 100.0% | 79.7% | 88.7 | 2.1 m |
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only, not a client project.
Each method answers a different question, and we use the lightest one that can answer it with enough confidence.
Compare the test data with reference data selected for the job, and document its limits.
Measure precision, recall, F1 score and offset, by area and at several tolerances.
Visit the sites where desk methods cannot settle what is on the ground.
These 12 sites were chosen from the largest differences, at least 1.5 km apart. A real plan would also confirm safe, legal access.
| Site | Why it was selected | Unit | Distance to test data | Status |
|---|---|---|---|---|
| Named stream not in test data (Emery Creek) | Black Creek | 249 m | Not visited | |
| Named stream not in test data (Humber River) | Black Creek | 143 m | Not visited | |
| Stream not in test data | Black Creek | 527 m | Not visited | |
| Stream not in test data | East Humber | 509 m | Not visited | |
| Stream not in test data | Black Creek | 504 m | Not visited | |
| Stream not in test data | Bolton Dam | 493 m | Not visited | |
| Stream not in test data | Black Creek | 484 m | Not visited | |
| Stream not in test data | East Humber | 483 m | Not visited | |
| Stream not in test data | West Humber | 483 m | Not visited | |
| Stream not in test data | Black Creek | 482 m | Not visited | |
| Stream not in test data | West Humber | 475 m | Not visited | |
| Stream not in test data | Bolton Dam | 470 m | Not visited |
A profile of one municipality's published water, sanitary and storm networks, built from real open data and measured with a metric suite.
Showing about 3.9 km by 4.2 km of the central area: 11,446 building outlines, 3,836 water mains, 7,074 sewer pipes and 776 main breaks. Zoom in for street names and individual assets. Building colours follow the published category: grey for residential, tan for commercial, brown for industrial and utility, and blue-grey for institutional and recreational. Line geometry is lightly simplified for display.
| Network | Pipes | Length (km) | Related assets |
|---|---|---|---|
| Water | 16,214 | 938.6 | 8,401 valves and 4,860 hydrants |
| Sanitary | 14,755 | 884.7 | 13,451 manholes and 25 active pumping stations |
| Storm | 21,863 | 835.6 | 18,662 manholes, 15,227 catch basins, 1,228 outlets and 169 facilities |
| Zone | Length (km) | Mains | Mean age | Valves | Hydrants | Main breaks, 2016 to 2025 |
|---|
Zone and owner names are generalized for this sample. Mean age is weighted by length. Each break is assigned to its nearest current main. Zones with under 1 km of main are left out.
This is the kind of metric suite we could build for a utility. These checks use only the published open data, so private fields a city holds internally could answer some of them.
Valves and hydrants whose related main ID exists in the published mains layer.
Gravity sewers with both an upstream and a downstream invert.
1.1% of gravity sewers with inverts record a lower upstream end.
Share of storm pipes with this code, compared with 0.5% of sanitary pipes.
Review means a person would check these items. It does not mean the records are wrong.
Each graph answers a practical question, using municipal open data retrieved on November 5, 2026.
Across 740 main breaks in 10 years, this grid shows where recorded breaks concentrate. It shows history, not a forecast, and small cells with little main can look high.
Point to a grid cell to see its values.
Cells with under 200 m of main are left out. Lines show mains of 300 mm or larger.
Straight-line distance from 16,767 published building outlines to the nearest hydrant, leaving out sheds, garages and utility buildings. This is a simple coverage measure, not a fire protection assessment.
We can build a suite from any of these, or improve the metrics your team already uses.
Finds broken ends, loose stubs and isolated parts of a network.
OutputConnected share, gaps by zone and traceable length
Measures required fields for each asset type and owner.
OutputFilled share by field, zone, asset class and age
Compares records with as-builts, GNSS points or field checks.
OutputOffset statistics and the source of each location
Tests sewer slopes, inverts, flow direction and connections.
OutputAdverse slopes, invert errors and low-capacity segments
For authorized staff, shows the valves needed to isolate each main, and who loses service.
OutputValves to close, customers affected and critical sites
Measures reach from hydrants, facilities or other service points.
OutputCoverage by area, and places outside the target distance
Combines age, material, break history, size and consequence.
OutputRanked renewal list, with likelihood and impact scores
Tracks delays, rejected readings and events without an asset match.
OutputLatency by source, match rate and feed health
On a client project, each of these would become a conversation with staff who know the system.
Only 9 of 8,401 valves and 24 of 4,860 hydrants refer to a main not found in the published layer.
No sanitary or storm pipe differs from its mapped length by more than our tolerance.
3,801 storm pipes, or 17.4%, use the code XXX. Filling this gap could improve renewal planning, if these are confirmed as unknown.
129 sanitary and 245 storm pipes record a lower upstream invert. These could be real conditions, survey differences or data entry issues.
4,213 storm pipes, or 19.3%, have an end ID not found in the storm manhole layer. Many may connect to catch basins, inlets or outlets, which a next step could test.
77.1% of main break records have a blank or unknown break nature. Better categories could make root-cause analysis more useful.
The published metadata says water features are not modelled as a true network, and that pipes are broken at road blocks. We therefore flag only 298 main ends that stop within 10 m of another main, as candidates for review.
A practical cleanup improves the data in stages, and every change stays traceable. Here is how these stages would apply to patterns found in this data.
Move mixed material values, such as Concrete and CP, to one list.
Fill missing inverts and materials from drawings, CCTV and field records.
Link pipes to all structures, and test them as a true network.
Add validation rules and QA/QC so new errors are caught early.
-- Flag gravity sewers that may slope the wrong way
SELECT sanpipeid
FROM sanitary_pipes
WHERE category = 'GRAVITY'
AND up_invert < dn_invert;This rule found 129 sanitary pipes in the published data.
This sample has no live feed. With a municipality, a real-time map would connect events to trusted asset records in five steps.
Open data published by a Canadian municipality under its open government licence, retrieved 2026-11-05. The municipality provides this information as is, and makes no warranty about its accuracy. Zone and owner names are generalized for this sample, and material descriptions are our reading of the published codes.
The pipeline behind our Humber River sample, from public web service to checked website data. We reran and tested it, and this page shows what happened.
Lineage shows where every output came from and what depends on it. Select an item to trace it through the pipeline.
A fingerprint is a short code calculated from a file's exact contents. If one byte changes, the code changes.
All of these figures were measured. Times are the median of three runs in a small cloud workspace with 2 processors and 7 GB of memory.
Total size of the data at each stage.
Clipping takes the longest. This excludes the original download and the separate tests.
A record that crosses a unit boundary becomes more than one clipped part. The web map leaves out waterbodies under 0.5 ha, and shows only 25 m contours.
A data contract states what each input must contain, so a change at the source is caught before it reaches a report or map. These profiles come from the source files in this run.
These checks test whether the pipeline did its job. They are separate from the 20 data issues in the Humber sample, which a person would review.
A check that always passes proves nothing. We deliberately damaged copies of the data, then ran the matching check.
The 2 misses are expected. These checks test structure and logic. They cannot tell that a believable position or value is wrong. That takes comparison with reference data or a field check, as shown in our dataset validation sample.
Simplifying lines makes a map fast, but it also moves them and shortens their mapped length. We tested seven tolerances on all 236,075 stream points to see how the 15 m tolerance used on our map compares.
At 15 m, the map keeps 9.0% of stream points, and no line moves more than 15 m. Going to 50 m would remove only 3.8% more of the original points, but would lose a further 5.8% of mapped length.
The web version is for display only. Lengths and areas are always calculated from the full geometry.
Humber River data from Land Information Ontario. Contains information licensed under the Open Government Licence – Ontario. Sample only.
Yes, for every stage after the download. Three runs produced identical files, which also match the files from the original run. A full rerun of the original script rebuilt the published web data in 23 seconds.
The web test file comes from the timed test stage. Check C15 separately confirms that the published web data can be rebuilt exactly.
A production pipeline should not rebuild everything when little has changed. To test the method, we changed 25 records, removed 3 and added 5 in a copy of the watercourses.
This tests the comparison only. These were test changes, not real updates from the source.
The results above are from a tested one-off run. This is how we would propose running a similar pipeline for a client. It has not been deployed or operated.
| Situation | Starting rule | Proposed response |
|---|---|---|
| Source is unchanged | Every record fingerprint matches the last run | Record the check and end the run |
| Source has small changes | Fingerprints differ for some records | Process affected records, then run all checks |
| Download is incomplete | Record count differs from the count reported by the source | Retry, then stop and alert the owner, keeping the last good data live |
| Source changes sharply | Record count moves by more than 2% between runs | Hold publication until a person reviews it |
| Source structure changes | Any data contract check fails | Stop before processing and alert the owner |
| Run becomes slow | Run time exceeds three times its baseline | Warn the owner, while allowing the run to finish |
| Output is too large | Web file exceeds its 1.5 MB budget | Stop publication and keep the last good version |
Each rule and threshold would be agreed with your team, based on how often your sources change.
Run on a schedule or when new data arrives.
Alert the right person when a step fails or a metric drops.
Keep earlier outputs and record what changed.
Provide documentation and tests your team can maintain.
Ontario Watershed Boundaries, Ontario Hydro Network (Watercourse and Waterbody) and Contour, from Land Information Ontario, retrieved November 2026. Contains information licensed under the Open Government Licence – Ontario.
Whether you need one map, a dataset or a full mapping product, we would like to hear about it. It is fine if the scope is still rough. Working that out is part of what we do.
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Last updated November 5, 2026
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