Sean Loos

In my experience this error occurs when the GeoTIFF has an internal mask. It works fine with an alpha layer, but not an internal mask.

Here is a simple script, zipped. The extension is .mb, and the syntax is similar to VB. The apostrophe is the comment character. Thanks for taking a look. [ScaleRuler.zip](https://github.com/oleg-shilo/codemap.vscode/files/5710741/ScaleRuler.zip)

I believe I have found the problem. In mapper_generic.js it is creating the "members" array, but it never sorts it. I added a sort on line 58 (before members.forEach) and...

In my experience, the problem is the internal mask. If your COG has an alpha channel it works fine but if you have an internal mask you get the AssertionError....

I ended up using an external alpha mask, and then using WebGLTileLayer with a GeoTIFF with multiple sources. TLDR: I wish OpenLayers/GeoTIFF.js supported internal masks :) My process could probably...

I've done some more testing using the COG sample (https://openlayers.org/en/latest/examples/cog.html). I changed the source to OSM, and I still see the same behavior when I zoom in to level 23...

Same issue. I worked around it by requiring "@petamoriken/float16": "3.4.7" in my package.json. Seems to be related to a newer release of float16.