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conveyal / r5

Developed to power Conveyal's web-based interface for scenario planning and land-use/transport accessibility analysis, R5 is our routing engine for multimodal (transit/bike/walk/car) networks with a particular focus on public transit
https://conveyal.com/learn
MIT License
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Custom accessibility index from logical combination of regional analysis layers #705

Open ansoncfit opened 3 years ago

ansoncfit commented 3 years ago

Users want to specify accessibility indices combining multiple destination types/counts/cutoffs/modes (e.g. access to at least 1 health clinic and 5 restaurants within a 20 minute walk, and 1 million jobs within a 45 minute transit trip). Preparing such an index is straightforward with basic raster operations in GIS.

At a minimum, we should show an example of this GIS workflow in the user manual guide.

Longer term, we could build these logical operations into our interface.

In terms of implementation, backend functions to fetch multiple regional analysis access grids and combine them in a specified way could be shared with https://github.com/conveyal/r5/issues/610

abyrd commented 3 years ago

The way to enable this immediately is to get the multiple layer download in #610 working and just add a tutorial on using the QGIS raster calculator. Doing the computations on the backend would require specifying how to combine the layers and there's a chance we'd just end up reinventing the QGIS raster math plugin.