Resampling always showing Nearest although other options are used

[lawrencenika]

Problem description

I tried with /cog/tiles/WebMercatorQuad/{z}/{x}/{y}.png?url=${encodeURIComponent(objPath)}&bidx=1&resampling=bilinear and a bunch of other resampling options like gauss or cubic but when zooming in to the image, they all look pixelated still which is from default resampling=nearest. Anything else I can try?

what i m seeing is

when resampling=bilinear

Expected Output

for resampling=bilinear

Environment Information

titiler:latest (v0.18.6) run in local docker env on macos
with ENV WORKERS_PER_CORE 1

[vincentsarago]

@lawrencenika would you be able to share the file you're working with?

[vincentsarago]

@lawrencenika there are 2 resampling at place:

• dataset reprojection
• dataset reading

each one are controlled by specific options: resampling and reproject.

you can try with resampling=bilinear&reproject=bilinear

[lawrencenika]

do I have to use them together? when I tried with resampling only, it failed

[vincentsarago]

what failed?

both control different things as I've explained. you can use them independently!

[lawrencenika]

when I tried with &bidx=1&resampling=bilinear it still returns the same pixelated image when zoom in, it might be my misconception but when I tried linear resampling in local desktop software for the same image, it returns the smooth image when zoomed in (shown in expected output section).

[vincentsarago]

tried linear resampling in local desktop software for the same image, it returns the smooth image when zoomed in (shown in expected output section).

Your local software might apply resampling after dataset read, which we don't support.

You can clearly see the effect of resampling when using the /preview endpoint

rescale=5000,11000&resampling=nearest&bidx=1&width=2048&height=2048

rescale=5000,11000&resampling=cubic&bidx=1&width=2048&height=2048

The resampling as a bit less effect when using the /tiles endpoint because you're doing reprojection on small chips which I why you should try seting reproject= but still you won't get the same result as you're get from you're local software (which is?)