grass VS OpenLayers3

https://grass.osgeo.org/

    GRASS GIS offers powerful raster, vector, and geospatial processing engines in a single integrated software suite. It includes tools for terrain and ecosystem modeling, hydrology, visualization of raster and vector data, management and analysis of geospatial data, and the processing of satellite and aerial imagery. It comes with a temporal framework for advanced time series processing and a Python API for rapid geospatial programming. GRASS GIS has been optimized for performance and large geospatial data analysis.

We haven't looked at integrating GRASS yet, as we're more interested in data display, not deep analysis. Just another example of a C/C++ library with front end bindings for Python. Numbers are crunched in C/C++, results returned to Python.

Anyone have good advice for where to learn how to use GRASS

Access: GRASS GIS

You probably know this, but in Google Maps at least, you can use browser zoom (ctrl/cmd +/-) to change the size of labels without zooming into the actual map.

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Speaking of maps, I got to work a fun zoom project a few years ago: https://map.fieldmuseum.org/

We used https://openlayers.org/ and thought long and hard about how to best handle zooming and variable levels of information density & visual hierarchy. If you zoom all the way out, we just highlight where the building is relative to the surroundings. As you start to zoom in, we start to highlight major exhibitions and entrances. Then as you zoom in more, we start showing recommended paths, smaller exhibitions, etc. The label sizes try to scale up and down at each level, smoothly, in order to balance readability and density.

Eventually you can reach the max zoom level and the labels will just grow bigger and bigger, but the SVGs dynamically shrink so they remain pictograms and not just contextless-lines.

Then if you keep going, you eventually find microscopic easter eggs :)

The code is pretty jank (and abandoned), but it's FOSS vanilla JS/HTML/CSS, and the only dependency is on OpenLayers: https://github.com/arcataroger/openlayers_indoor_map

In order to display the GeoJSON features on a map, we will use OpenLayers, which is a very powerful open-source mapping library that is also very simple to use.

OpenLayers is available via the ol npm package, offering developers a powerful toolkit for creating sophisticated maps. Here is a JavaScript implementation that utilizes OpenLayers to showcase a map:

Official Website: https://openlayers.org/

For web maps I'd strongly recommend using OpenLayers. While it's less convenient to get started with compared to the alternatives it's also much more feature-complete and you'll likely hit a ceiling in terms of functionality much later than you would with the others.