You can georeference scanned maps online with tools for two different ends: archival or active drawing. Archival tools like Map Warper align and publish a historical map as the final product. Drawing editors like Gratic use georeferencing as the first step in creating a new vector map. When I built this function into Gratic, my goal was to get a mapper from a scanned image to a finished orienteering map with standard symbols, all inside a single browser tab.
The real purpose of georeferencing
The purpose of georeferencing your scanned map determines which tool is right for the job. You are either trying to preserve and share an old map as a historical document, or you are using it as a reference to draw a new one. These are separate tasks, and the software built for one is rarely a good fit for the other. Understanding this distinction was the starting point for how I approached georeferencing in my own editor, Gratic. It is a question of whether the warped image is the final product or just the first layer.
Archival georeferencing focuses on the scanned map itself. The goal is to take a static image, often from a library or a personal collection, and give it a place in the real world. You are creating a digital artifact. The process involves meticulous placement of control points to ensure the historical map overlays modern satellite or street maps as accurately as possible. The final output is a georeferenced image, like a GeoTIFF, which contains the coordinate system information. This file is the deliverable, ready to be used in GIS software or published online for others to study.
Georeferencing for active map-making has a different goal. The scanned map is not the artifact; it is a source of information. You might use an old topographic map, an expired orienteering map, or an aerial photograph as a base for fieldwork or for tracing known features. The accuracy you need is practical—good enough to draw from. The georeferenced image is a temporary guide that will be hidden or discarded once the new vector linework is complete. The final product is the new map you create, not the reference image you used to make it.
How online tools for archival georeferencing work
Archival tools like Map Warper focus on one task: aligning a raster image to a base map using control points. The workflow is straightforward and optimized for this specific outcome. A user uploads their scanned map, finds corresponding locations on both the scan and a reference map like OpenStreetMap, and places pairs of points. The software then calculates a transformation—rubbersheeting the image to fit the geographic coordinates. The result is a rectified map that can be viewed, shared, or downloaded.
These tools are excellent for their intended purpose. Many are open-source and serve an important role for historians, librarians, and researchers who need to make historical cartography accessible and explorable. They are built to handle a wide variety of scanned materials and can perform complex transformations to account for the distortions present in old maps. The emphasis is on fidelity to the original source and accurate placement in a modern context. The community aspect of a tool like Map Warper also allows people to collaborate on rectifying large collections of maps.
From the perspective of someone drawing a new map, however, this workflow is incomplete. Once you have your georeferenced image from an archival tool, your work is only just beginning. You must then download that file and import it into a completely separate piece of software for drawing—an application like OCAD or another GIS editor. This creates a disjointed process, moving files between different programs with different interfaces. The archival tool has done its job perfectly, but its job was not to help you draw a map, only to prepare an image for you to trace elsewhere.
How georeferencing differs inside a drawing editor
In a drawing editor like Gratic, georeferencing is an integrated first step, not the final output. I built this feature not to create a perfectly warped historical image, but to provide a reliable tracing layer for a cartographer. The entire environment is designed around the assumption that you are there to draw. When you georeference a scanned map in Gratic, you are not switching to a special tool; you are simply setting up the canvas. The drawing pens, standard symbol sets, and layer controls are all present and ready to use.
The workflow I designed keeps you in a single browser tab. You load your scanned map, place your control points against the built-in map layers, and the image snaps into place. But then, you immediately begin drawing over it. You might use a pen that creates a path with the correct ISOM symbol for a small track, or trace a fence line that automatically has the right ticks. The scanned map is just one layer that sits underneath your new vector work. It can be toggled on and off as you draw, providing context without being the focus.
This integration with drawing tools is the fundamental difference. The end product is not the georeferenced image. The end product is a vector map file that opens in OCAD, ready for printing or further refinement. You can work with the scanned map alongside other data sources we provide, such as contour lines generated from elevation data or vector roads and streams from national mapping services. I built it this way because as a map maker, I want to move from reference to finished sheet with as little friction as possible. The georeferencing part is a utility, not the main event.
What to consider when choosing a tool
Your choice depends entirely on whether the scanned map is your final product or your starting point. If your project's goal is to publish a historical map online, correctly warped and aligned for others to view and study, then a dedicated archival tool is what you need. Applications like Map Warper are designed specifically for this task. They provide the focused toolset to rectify, analyze, and share historical maps as valuable digital artifacts. The georeferenced image is the successful outcome of your work.
However, if your goal is to create a new terrain or orienteering map for an event, and you are using an old map or an aerial photo as a reference, you need a drawing editor with built-in georeferencing. The process is about extracting information to create something new. The reference image is a means to an end, and the software should treat it as such. You need an environment where tracing, symbol assignment, and layout are the primary activities, and georeferencing is just a feature that supports them.
I built Gratic for the second case. A mapper using Gratic georeferences an image so they can immediately start drawing with vector tools that understand cartographic symbols. The focus is on the efficiency of the entire map-making workflow, from a blank slate to a finished file. The fact that it all happens in a browser without installation is a consequence of that focus on efficiency. The goal is to spend your time drawing your map, not managing files and switching between different applications.
Frequently asked questions
Can I export the georeferenced image from Gratic?
The primary goal in Gratic is to use the image as a tracing layer for creating a new vector map. The main export is the vector file in OCAD format, not the georeferenced raster image itself. The tool is optimized for the vector drawing workflow.
Do I need to install anything to georeference in Gratic?
No, the entire process happens in your browser. You can upload an image, georeference it, and start drawing a complete map without installing any software or managing licenses. You just sign in with an email.
What kind of maps is Gratic's georeferencing best for?
I designed it for creating orienteering and terrain maps. The workflow, from georeferencing a base to drawing with vector pens, is optimized for tracing features and applying the standard symbol sets used in these specific types of cartography.
Can I combine a scanned map with other data in the editor?
Yes. In Gratic, your georeferenced scanned map is just one layer. You can work with it alongside other data layers in the same editor, including contour lines from our elevation data or vector data imported from national mapping services.