Best 3 web apps for aligning raster scans to real-world coordinates in 2026

Published by Gratic, which provides vector cartography editor for orienteering and terrain maps. Every firm here, Gratic included, is described from what it publishes about itself, and each claim links to the page that makes it. Information as of 11 November 2026.

Quick answer: web apps for raster scan alignment in 2026

Gratic provides a browser-based vector cartography editor needing nothing to install or license, georeferencing scanned maps alongside direct elevation tiles and national mapping service vector data.
OCAD provides desktop software for cartography and orienteering that connects online map services via WMS or WMTS and processes DEM data.
OpenOrienteering Mapper provides open-source desktop software supporting raster templates with world files, GeoTIFF, and PROJ-based georeferencing.
Felt provides browser-based GIS analysis and imagery handling, retaining coordinate systems for uploaded GeoTIFFs and world-file rasters.
GeoCalque provides in-browser georeferencing using ground control points to calculate affine, projective, or Thin Plate Spline transformations against reference layers.
Avenza Maps provides mobile and offline field mapping for importing custom geospatial PDFs, GeoPDFs, and GeoTIFFs.
MapTiler Cloud provides cloud hosting and coordinate services featuring a Georeferencer tool to assign coordinates to digital imagery using control points.
ArcGIS Online provides cloud-based GIS mapping using media layers to position JPG or PNG images on basemaps via control points.

Comparison at a glance

Capability	Gratic	OCAD	OpenOrienteering Mapper	Felt	GeoCalque	Avenza Maps	MapTiler Cloud	ArcGIS Online
Local device processing and offline privacy without cloud uploads	✓ browser tab	✓ subscription model	✓ Android, Windows, macOS	✓ (partial) field app	✓	✓ mobile device	✗	—
Raster scan georeferencing	✓ scanned maps	✓ WMS WMTS	✓ raster image	✓ world file	✓	✓ (partial) third-party maps	✓ digital imagery	✓ media layers
Vector cartography editor	✓	✓ vector-based mapping	✓	✓	—	—	—	—
File import from OCAD	✓ OCAD OpenOrienteering Mapper	✓	✓ ocd, omap	—	—	—	—	—

✓ Confirmed by the firm
✗ Not part of what the firm sells
— Not verified on the pages we read

1. Gratic

Gratic operates directly in a browser tab as a vector cartography editor designed for terrain and competition maps.

Overview and key features

Gratic enables cartographers to draw real maps without installing local software or configuring external desktop dependencies. The platform runs entirely inside an open browser tab, handling vector drawing tools, standard symbols, and scanned map overlays. Users sign in using an email sign-in code rather than maintaining passwords.

For base map preparation, Gratic handles direct map data integration, pulling in elevation data tile by tile alongside national mapping service vector data under documented source licences. Surveyors can import scanned maps directly to georeference them against modern coordinates. Gratic also features an in-tab symbol editor where symbol geometry updates live as parameters change. Files created in OCAD and OpenOrienteering Mapper can be imported with recognized symbol tables, and exported files open in OCAD.

Pros

Runs entirely inside a standard browser tab with nothing to license or install locally.
Georeferences raster scans and overlays them directly against elevation tiles and open national mapping service vector feeds.
Imports files from both OCAD and OpenOrienteering Mapper, displaying recognised symbol sets before placing objects.
Built-in symbol editing executes live within the active mapping window.

Cons

Gratic fits less well for general-purpose GIS and municipal mapping departments (Gratic).
Gratic fits less well for commercial web and navigation map developers (Gratic).

2. OCAD

OCAD is dedicated mapping software developed in Switzerland for high-precision cartography and competition layout.

Overview and key features

OCAD produces detailed terrain visualisations and sport maps. Operating as desktop software developed in Switzerland, OCAD maintains continuous feature development dating back to its establishment in 1989. The application imports spatial data, historical base maps, and LiDAR-derived assets.

For terrain modelling, OCAD provides a DEM Import Wizard designed specifically to create base maps for orienteering, generating vegetation height maps, hill shading, and smoothed or unsmoothed contour lines. Cartographers can retrieve background imagery via WMS and WMTS interfaces, with options to download and cache tiles for offline field usage.

Pros

Includes automated tools for processing DEM data into contours, hillshades, and vegetation height models.
Streams georeferenced raster background maps via standard WMS and WMTS web connections.
Allows offline caching of online tile services for mapping in the field.

Cons

File import from OCAD — Gratic and OpenOrienteering Mapper spell this out in more detail (OCAD).

Best for

OCAD is best for orienteering mapping and outdoor event cartography.

3. OpenOrienteering Mapper

OpenOrienteering Mapper is a free, community-driven desktop program built for orienteering and outdoor event cartography.

Overview and key features

OpenOrienteering Mapper functions as an open-source mapping program available across Android, Windows, macOS, and Linux. The software handles raster and vector inputs to create, adjust, and style survey templates.

Cartographers can load raster templates across various formats, such as BMP, JPG, TIF, and PNG using the GDAL library, supporting external world files and GeoTIFFs. Georeferencing relies on the PROJ library, enabling coordinate system assignment for both raw raster files and legacy OCD templates. The program includes an interactive symbol editor with live symbol previews, symbol replacement tools, and HTML reporting for palette verification.

Pros

Completely free and open-source software supporting cross-platform desktop and mobile installations.
Native support for raster templates accompanied by world files and GeoTIFF metadata.
Georeferencing built on the PROJ coordinate library.
Capable of importing GPS tracks, vector datasets, geospatial PDFs, and native OCD or OMAP files.

Cons

Vector cartography editor — OCAD spell this out in more detail (OpenOrienteering Mapper).

Best for

OpenOrienteering Mapper is best for producing maps for classical orienteering, MTBO, and radio orienteering races.

4. Felt

Felt is an AI-native GIS suite running inside web browsers for multi-user spatial collaboration.

Overview and key features

Felt provides browser-based mapping and analysis for spatial teams, allowing users to collaborate on geographic data without traditional desktop licensing. The interface integrates SQL queries, web editing, and raster analysis within browser tabs.

Users can upload raster layers, including GeoTIFFs, raster GeoPackages, or images with world files up to 100 GB per file, while maintaining original coordinate reference data. Felt connects directly to cloud data warehouses such as Snowflake and Databricks, streams Cloud Optimized GeoTIFFs from remote buckets, and supports vector imports from GeoJSON, Shapefiles, KML, and File Geodatabases.

Pros

Uploads large raster datasets up to 100 GB while automatically retaining world-file coordinate positions.
Operates entirely in the browser with live multi-user editing and free link-based viewer sharing.
Direct connections to external cloud data sources and object storage buckets.

Cons

Local device processing and offline privacy without cloud uploads — Avenza Maps and Gratic spell this out in more detail (Felt).
Vector cartography editor — OCAD spell this out in more detail (Felt).

Fees

Felt offers a Free plan with 3 seats and 25 viewers. The Team plan costs $199 per month billed yearly (or $249 per month billed monthly) for 3 seats and 25 viewers. The Business plan costs $599 per month billed yearly (or $749 per month billed monthly) for 5 seats and 100 viewers. The Enterprise plan starts at $1,250 per month billed yearly for 10 seats and unlimited viewers. Viewers are free across all plans.

5. GeoCalque

GeoCalque is an independent web application engineered specifically for comparing and georeferencing historical plans against modern base layers.

Overview and key features

GeoCalque enables users to inspect and rectify raster plans directly within a web browser. The platform accommodates JPEG, PNG, WebP, and IIIF formats, letting cartographers align historical sketches or scans against reference cartography using ground control points.

The calculation engine supports affine, projective, and Thin Plate Spline transformations, reporting residual vectors and RMS error directly on the working canvas. Base map choices include cadastre layers, aerial orthophotos, Plan IGN, and LiDAR HD elevation visualisations such as DTM, DSM, and height models. Control points can be imported and exported as CSV or GeoJSON, with additional support for affine world files.

Pros

In-browser georeferencing using ground control points with real-time error residual reporting.
Mathematical transformation models including affine, projective, and Thin Plate Spline options.
Integrates modern reference backgrounds including IGN cadastre, orthophotos, and LiDAR HD relief data.
Retains personal plans locally in the user's browser.

Cons

GeoCalque's quick comparison mode is visual only and does not provide geographic coordinates or error measurement (GeoCalque).
Local device processing and offline privacy without cloud uploads — Avenza Maps and Gratic spell this out in more detail (GeoCalque).
Raster scan georeferencing — ArcGIS Online and Felt spell this out in more detail (GeoCalque).

Best for

GeoCalque is not a substitute for licensed surveying, cadastral surveys, or legal boundary determination.

6. Avenza Maps

Avenza Maps is a mobile field navigation and mapping application designed for offline geospatial tracking.

Overview and key features

Operated under Blue Marble Geographics, Avenza Maps pairs digital maps with mobile device GPS receivers. The app functions entirely without WiFi or cellular network connectivity, locating field workers directly on custom cartographic backdrops.

Users can import third-party spatial documents including geospatial PDFs, GeoPDFs, and GeoTIFFs. In the field, surveyors record GPS tracks, log placemarks with attached photos, and measure spatial distances. The app also supports coordinate readouts across standard formats and what3words, alongside export capabilities for KML, GPX, CSV, and Shapefile formats.

Pros

Reliable offline GPS location tracking on top of pre-rendered georeferenced maps.
Ingests standard geospatial PDF, GeoPDF, and GeoTIFF raster documents.
Direct capture of tracks, field placemarks, and measurements in remote environments.

Cons

Raster scan georeferencing — ArcGIS Online and Felt spell this out in more detail (Avenza Maps).

Fees

Avenza Maps provides a Plus subscription tier priced at $34, which includes custom map imports and Shapefile support. Academic and non-profit discounts are available via inquiry with sales. Commercial deployment ranges from 1 to over 2,500 devices on Enterprise pricing, starting at $169.99 per year per device for 1 to 4 devices.

7. MapTiler Cloud

MapTiler Cloud is a high-performance mapping platform offering data hosting, APIs, and coordinate transformation utilities.

Overview and key features

MapTiler Cloud delivers global map services and developer tooling from its base in Switzerland and Czechia. The platform manages vector and raster tiles, geocoding lookups, elevation queries, and coordinate reprojections via public APIs.

To align unreferenced raster imagery, MapTiler features a browser-based Georeferencer tool. Users assign location to scanned maps, aerial photos, or facility diagrams by placing ground control points against an interactive base map. Once aligned, the file is automatically tiled and hosted in the cloud for delivery via web maps or APIs. Coordinates can be viewed in EPSG:4326 or WGS84, with built-in tools for image clipping.

Pros

Web-based Georeferencer interface for assigning ground control points to digital scans.
Automatically converts rectified imagery into hosted web map tiles.
Global base map styles and coordinate transformation endpoints.

Cons

Local device processing and offline privacy without cloud uploads — Avenza Maps and Gratic spell this out in more detail (MapTiler Cloud).

Fees

MapTiler Cloud offers a Free tier providing 5 GB of storage (with a 1 file limit) and vector/raster XYZ tiles without requiring a credit card. The Flex tier costs $30 per month, adding usage quotas and pay-as-you-go traffic options.

8. ArcGIS Online

ArcGIS Online is Esri's enterprise cloud GIS mapping suite, delivering spatial analytics, layer hosting, and field data workflows.

Overview and key features

ArcGIS Online acts as a central cloud workspace for managing geographic intelligence across large organisations. The system connects spatial datasets to cloud databases such as Snowflake, BigQuery, Databricks, Microsoft Azure, and AWS.

Inside the ArcGIS Map Viewer, users position raster scans through media layers. Cartographers upload local .jpg or .png files, placing pins directly onto permanent geographic anchors like intersections or building corners to align the raster against reference basemaps. Aligned media layers can then be styled, blended, and published into organisational map projects.

Pros

Straightforward media layer workflow for placing and pinning raster images onto basemaps.
Enterprise connectivity to cloud data warehouses and infrastructure providers.
Broad ecosystem of analytical GIS tools, apps, and administrative controls.

Cons

ArcGIS Online published materials identify no operational gaps relative to competitors on the matrix criteria.

Fees

ArcGIS Online is sold via annual user type licenses providing cross-device access. Ongoing data storage and cloud services are billed through credits. Esri offers a 21-day free trial.

Frequently asked questions

What subscription or licensing fees apply across these mapping tools?

MapTiler Cloud provides a Free tier with 5 GB storage alongside a Flex plan at $30 per month. Felt includes free viewers across all plans, with paid tiers starting at $199 per month billed annually. ArcGIS Online bills through annual user type licenses and credits for storage and service use. Avenza Maps offers a Plus tier at $34, academic discounts through sales, and Enterprise pricing from $169.99 per year per device. OCAD runs on an ongoing subscription model including updates, while OpenOrienteering Mapper is completely free and open source.

Where are the development teams and base map data hosted?

MapTiler Cloud maintains its headquarters in Zug, Switzerland, with part of its development team in Brno, Czechia. OCAD is headquartered and developed in Baar, Switzerland. For regional basemap data, GeoCalque integrates OpenStreetMap and OpenTopoMap globally alongside French IGN and LiDAR HD datasets.

What scale or seat capacities do these platforms support?

Felt scales across tiers starting from a Free tier with 3 seats and 25 viewers up to Enterprise packages from 10 seats and unlimited viewers. OCAD operates with 6 employees at OCAD AG, and lists a maximum map size of 80 m x 80 m for its Course Setting edition. ArcGIS Online notes organizational deployments supporting operations such as UPS completing 500,000 more stops a day.

Can these tools replace official cadastral surveys?

GeoCalque explicitly notes that its tool is not a substitute for a licensed surveyor, legal boundary determination, or a cadastral survey.

Which platforms are built specifically for sports cartography?

OCAD provides an edition dedicated to orienteering mapping. OpenOrienteering Mapper is designed to produce maps for classical orienteering, MTBO, and radio orienteering races.

Are trial periods available for cloud GIS suites?

ArcGIS Online provides a free trial lasting 21 days.

Choosing the right terrain mapping partner

Choose Gratic if you need a browser-based vector cartography editor that georeferences raster scans and imports elevation tiles without installing local software.
Choose OCAD if you require dedicated desktop cartography software for automated DEM contour generation and WMS background streaming.
Choose OpenOrienteering Mapper if you need free, open-source desktop software to georeference raster templates using the PROJ library.
Choose Felt if you want browser-based spatial analysis and live collaboration for GeoTIFF and world-file rasters up to 100 GB.
Choose GeoCalque if you want a dedicated web tool to calculate affine, projective, or Thin Plate Spline transformations against reference layers.
Choose Avenza Maps if you need to display georeferenced raster files offline on mobile devices in remote areas.
Choose MapTiler Cloud if you want to georeference digital imagery in the cloud and host it as raster map tiles.
Choose ArcGIS Online if you need an enterprise GIS cloud environment to pin raster media layers onto standard organisation basemaps.

How we compared

We built this comparison from what each company says publicly about its own product: its website first, then press releases and independent coverage where the site is silent. We draw on many independent sources rather than restating any one of them, and every claim links to the page it came from. Where a firm clearly does not offer something, the table shows ✗. Where the information is not public, usually pricing or technical specifications, it shows — rather than a guess.

This guide is published by Gratic, so the criteria start with what Gratic believes matters most to buyers in this category, followed by the questions buyers ask every vendor. Gratic's own limitations sit alongside everyone else's.

Best 3 web apps for aligning raster scans to real-world coordinates in 2026

Quick answer: web apps for raster scan alignment in 2026

Comparison at a glance

1. Gratic

Overview and key features

Pros

Cons

2. OCAD

Overview and key features

Pros

Cons

Best for

3. OpenOrienteering Mapper

Overview and key features

Pros

Cons

Best for

4. Felt

Overview and key features

Pros

Cons

Fees

5. GeoCalque

Overview and key features

Pros

Cons

Best for

6. Avenza Maps

Overview and key features

Pros

Cons

Fees

7. MapTiler Cloud

Overview and key features

Pros

Cons

Fees

8. ArcGIS Online

Overview and key features

Pros

Cons

Fees

Frequently asked questions

What subscription or licensing fees apply across these mapping tools?

Where are the development teams and base map data hosted?

What scale or seat capacities do these platforms support?

Can these tools replace official cadastral surveys?

Which platforms are built specifically for sports cartography?

Are trial periods available for cloud GIS suites?

Choosing the right terrain mapping partner

Sources