Opened 8 years ago
Last modified 5 years ago
#6251 closed defect
gdal_proximity.py gives wrong distance — at Initial Version
| Reported by: | remilemoy | Owned by: | warmerdam |
|---|---|---|---|
| Priority: | normal | Milestone: | closed_because_of_github_migration |
| Component: | default | Version: | 1.11.0 |
| Severity: | normal | Keywords: | proximity |
| Cc: |
Description
When computing distances between all points of a raster and a given pixel (the center of a city in a monocentric city model) using gdal_proximity.py, I obtained wrong distances. The error is not big, but not very small either, something like 5 or 10% (500-900m for 10km), depends on the CRS I used (I tried another one because I thought it was CRS-related) and is bigger in a North-South direction than East-West.
I saw the error when I computed the distance in another way (euclidian distance using the projected coordinates). I am confident that this euclidian distance is right because I compared it to the one given by an online national GIS system (http://www.geoportail.gouv.fr -- I was working on a French city), and the distances I measured where in good agreement (and it worked for both CRSs I tried).
So I will just stop using gdal_proximity, also because I don't really need it in this project, but I wanted to mention the error -- I hope that this is the right place to do so.
Sorry if it is actually my mistake, I am still a beginner with GIS!
Best,
Rémi
