can i use `splatEncoding` to get more precision in the spherical harmonics?

[DethRaid]

hello!

i've been looking at using spark for a project, but i'm running into an issue. when i pass sh3 data to spark, i get splotches of green or red in areas of my model with bright specular highlights

my sh3 coefficients are very small - most have an absolute value well below 0.017, so they result in a value of 0 when packed into a six-bit signed integer. i noticed that i can pass a splatEncoding object to the PackedSplats constructor - https://github.com/sparkjsdev/spark/blob/main/src/PackedSplats.ts#L87. then the dyno code can pull those values when reading spherical harmonics, i think. i normalized my spherical harmonic coefficients, passed the normalization factors to spark in a SplatEncoding object, and.... the problem was worse

some debugging in the chrome debugger reveals that the splat encoding object is being overwritten after a PackedSplats constructor runs? but i'm struggling to find where in the spark code that's happening or how to stop it

so, enough rambling. some specific questions:

• can i somehow normalize my spherical harmonic coefficients and tell spark about the normalization factors, in order to get better precision?
• is there another way i might get better precision in sh3? i've seen a draft pr Interleave spherical harmonics coefficients #146 that would make all the packed spherical harmonics use eight bits. that'd help, but for my particular assets the problem may still exist

thanks in advance for any help yalls can provide!

[DethRaid]

been poking at this a bit more. if i pass my SplatEncoding object to my SplatMesh instead of PackedSplats, the sh scaling has an effect - but i'm still not getting the results i want. i'm continuing to work at it

[DethRaid]

i can't get the spherical harmonic coefficient scaling to work. gonna shelve this and take another approach. i'd still really appreciate some guidance on using the SplatEncoding object, though

is there perhaps a better way to get support with using this library?

[dmarcos]

Try #81 (comment)