Refine grid dist calculation

ObjectVision / 2BURP

Towards Build Urban and Rural Projections

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Refine grid dist calculation #28

Closed cjacobscrisioni closed 7 months ago

cjacobscrisioni commented 7 months ago

Grid dist calculations

[x] Determine if projection should be LatLong {earlier version stated WebMercator)
[x] Ideally are based on a % within water grid, not 0/1.
[x] Incorporate country borders (through a sizeable penalty, see https://forobs.jrc.ec.europa.eu/gam/sources)
[x] Swap settlement centroids for settlement polygons (to account for multiple acceptable startpoints in larger settlements)

cjacobscrisioni commented 7 months ago

Adjusted network-based calculations, swapping start- and endpoints. See d450536..feedfc1. Very good performance now.

MaartenHilferink commented 7 months ago

Webmercator: As all other calculation are done in WGS84 (LatLong) (with the exception of connect to road vector data, which is done in WebMercator), I think this operation should also be done in WGS84; for this, using latitude specific aspect ratio's has been filed as feature request at https://github.com/ObjectVision/GeoDMS/issues/673

cjacobscrisioni commented 7 months ago

Webmercator: As all other calculation are done in WGS84 (LatLong) (with the exception of connect to road vector data, which is done in WebMercator), I think this operation should also be done in WGS84; for this, using latitude specific aspect ratio's has been filed as feature request at ObjectVision/GeoDMS#673

@MaartenHilferink can you already share the latitude specific aspect ratio's / formula? So I can include them in the network-based approximation.

jipclaassens commented 7 months ago

Concerning borders. @MaartenHilferink is working on something to include districts (https://github.com/ObjectVision/GeoDMS/issues/673)

MaartenHilferink commented 7 months ago

@cjacobscrisioni

See progress in https://github.com/ObjectVision/GeoDMS/issues/673 for latitude_specific variants, which are implemented in https://github.com/ObjectVision/GeoDMS/releases/tag/v14.15.3
Zonal barriers on the way and planned to be in v14.15.4.
formula for lat-long: original := 0.5(impGrid[location]+impGrid[adjacentCell]); factor := cos(latitude pi / 180.0)
- distance between two north-south rasters: original
- distance between two east-west rasters: original * factor
- distance between two diagonally connected cells: original sqrt(1+factor factor)
see lines 310 jo 317 in https://github.com/ObjectVision/GeoDMS/releases/tag/v14.15.3
I intend to replace cos(latitude) by PJ_FACTORS ::meridional_scale resulting from proj_factors, but this hasn't been working yet.

MaartenHilferink commented 7 months ago

I'll add examples in /Preprocessing/GridDists/AccessGrids_grid/gggg/xxxx that refer to

/SourceData/RegionalUnits/Countries/per_grid

to determine zonal boundaries and use 25f as the configured value for the zonal boundary impedance

MaartenHilferink commented 7 months ago

See https://github.com/ObjectVision/GeoDMS/releases/tag/v14.15.4 and latest commit of 2BURP

cjacobscrisioni commented 7 months ago

Tested all implemented versions, all working perfectly now. Still need to decide whether to stick with the network-based variant or one of the costs versions (will depend on calibration tests as well). Latitude-corrected versions show sizeable differences even in Denmark, indicating the relevance of doing so. Thanks!