Interpolate values when "overzooming" dataset ?

[tdurand]

Hello,

I am working with the Copernicus DEM dataset (10m), and I am facing this problem, when I request a tile that is too "zoomed in" regarding of the accuracy of the dataset, titiler just set the same value in the nearest pixels, is there a way to interpolate values ?

For example, this tile from the copernicus DEM (10m resolution) tiled by titiler (zoom 15 over Rio de Janeiro):

https://titiler.xyz/cog/tiles/WebMercatorQuad/15/12450/18531.png?url=https://copernicus-dem-30m.s3.amazonaws.com/Copernicus_DSM_COG_10_S23_00_W044_00_DEM/Copernicus_DSM_COG_10_S23_00_W044_00_DEM.tif&algorithm=terrarium

And the exact same tile from the mapzen dataset that seems to interpolates values (30m resolution in brasil from SRTM dataset, data for mapzen terrarium on this area is less accurate than copernicus dem):

https://s3.amazonaws.com/elevation-tiles-prod/terrarium/15/12450/18531.png

I want to interpolate values because when using titiler, depending on the latitude on earth, the max zoom corresponding to the source data 10m horizontal resolution can be different between 11 , 12 and 13 for z value.

Thanks a lot, happy to provide more context if this isn't clear.

Thibault

[vincentsarago]

You can use reproject and resampling` options but this is not dynamic (meaning it cannot depends on the zoom level)

https://titiler.xyz/cog/tiles/WebMercatorQuad/15/12450/18531.png?url=https://copernicus-dem-30m.s3.amazonaws.com/Copernicus_DSM_COG_10_S23_00_W044_00_DEM/Copernicus_DSM_COG_10_S23_00_W044_00_DEM.tif&algorithm=terrarium&resampling=bilinear&reproject=bilinear

[tdurand]

Nice !! I just found out about those params thanks to ChatGPT by giving the link of my own question 🙃 but you were faster !! may this help someone else in the future.

Seems I need to update my titiler instance that seems to be too old to support those params, but it should do the trick.

Regarding the zoom level, I see what you mean, I guess if I want to make it dynamic I can do it on my side (by adding or not reproject and resampling on the request depending on zoom level)

many thanks again and have a great day !

[vincentsarago]

VincentGPT ;-)