Feature request - enable Distance to be set for -c, --filterByValue name,cmp,value

[murcje]

Hi!

I noticed that is not yet possible to filter based on Distance. When using splat-transform splat.ply -c distance,lt,100 splat.compressed.ply I get the following error:

Cannot read properties of null (reading 'hasColumn')

Would be great to be able to filter based on distance. MCMC splats tend to be very large and have lots of useless gaussians in the relatively far distance. This decreases accuracy when viewed in web viewers.

Thank you!

[murcje]

It also seems that filtering based upon opacity using for instance splat-transform splat.ply -c opacity,gt,0.01 splat.compressed.ply defaults to filtering by a value of 0.5

[slimbuck]

Hi @murcje,

Distance does not appear as a column in PLY files, which is why it doesn't currently work. Distance is actually a generated value in SuperSplat editor and I guess we should consider adding these to splat-transform too.

You can accomplish a similar result by filtering based on x, y and z columns separately. This will give you the bounding box instead of bounding sphere. You would do something like -c x,lt,10 -c x,gt,-10 -c y,lt,10 -c y,gt,-10 -c z,lt,10 -c z,gt,10 (completely untested, take with a pinch of salt).

Regarding opacity, these are actually stored as a sigmoid value in PLY. To get actual opacity you must use the conversion we do here.

Again, SuperSplat presents opacity as a normal value after converting from the native data.

I suppose by default we should convert these columns to expected values for purposes of filtering (perhaps the option can be controlled by a global flag).

Let me know if you need anything else to accomplish what you need now.

Thanks!

[slimbuck]

Just to add, if you want to filter by 0 < opacity < 1, use the value -Math.log(1 / opacity - 1).

(We do this in the engine too here).

[murcje]

@slimbuck Thank you for your answers. I naively assumed that the columns referred to the parameters by which you can filter gaussians in Supersplat.

The bounding box would work, but gives a visually distinct rectangular edge. Where spherical would allow for a more horizon-like edge. This matters mostly for landscape captures I guess.

Using your opacity filter advise, how would I format my cmd string to filter out all gaussians with an opactity of less than 0.1?

splat-transform splat.ply -c opacity,gt,-Math.log(1 / opacity - 1) splat.compressed.ply is not working> please forgive my ignorance in these matters of math and code

[slimbuck]

To filter by opacity 0.1 you'd calculate -Math.log(1 / 0.1 - 1), which is -2.2 and then go:

splat-transform splat.ply -c opacity,gt,-2.2 splat.compressed.ply