rendering houdini volume with any vector grid Tweet

[bloomendale_1]

Hi
i'm trying to render my density volume with any vector grid (vel.*) and ipr renders just a portion of my cam frustum zoomed into full ipr window. it's like i'm rendering from a different camera.
i haven't tested it with all possible variations, but just duplicating and merging the same density field didn't break anything. but when you add even empty vector fields it uses wrong frustum to render

win10, h17.0.352, Octane 4.00.0.16, 4.00 RC6
1080ti + 970

[juanjgon]

Hi,

I'm not sure to be able to reproduce this problem here. Can you please send me a scene (as simple as possible) to reproduce it?

Thanks,
-Juanjo

[bloomendale_1]

hi
sorry for a late reply
i can't send scenes from that computer.
but you can recreate it:
create a sphere, convert to density through vdb or isoOffset, merge with empty vector volume (i guess name attrib is not important, you can try "vel") and try to render from cam.
in my case it renders fine (matches what i see through camera in viewport) if only scalar field is present, as soon as you add vector field it starts to render only portion of the image plane - it's like it changes focal length drastically (i tried to zoom out in IPR with mouse wheel but it looked waaaay too deformed)
that's it.

UPDATE:
so, even when i add a scalar field with different name (even empty) it breaks.
1) scalar "density" (or anything that matches name in Octane tab on obj node) - renders fine
2) scalar "density" + scalar "any" / vector "any" - renders weirdly.
3) scalar "density + scalar "any" / vector "any" + scalar "density" - yes, 2 "density" fields - renders fine (but i can't make vector field to work as velocity - no mblur)

[bloomendale_1]

Any update?

[juanjgon]

I'm still investigating this issue. I think that the main problem is that you are using grids that don't have the same voxel scale, and probably this is breaking the volume extraction bounding box and transformations data. In Octane all the grids must have the same voxel scale.

Have you tried to use grids all with the same voxel scale (not empty volumes or something like that)?

Thanks,
-Juanjo

[bloomendale_1]

thanks for looking into it.
yes, looks like there is problem with bbox or even centroid, cause sometimes it renders incorrectly if vel field has different dimensions
i attached a hip file for you to look at

Is there a way to render vel field with different resolution? Cause 99% of the time we don't need that much data in vel field for mblur and they are pretty heavy. 25% res would suffice.

And one more thing - is there a control to change mblur settings - like backward-centerd-forward? found only shutter time. cause i noticed even when i managed to render my test volumes with mblur it still moves it a bit, but not knowing mblur settings i'm not sure if it's a bug or not.

Thanks

UPDATE: not sure if my hip file uploaded - can't find where to look. is it possible to attach something but image at all?

[juanjgon]

Is there a way to render vel field with different resolution? Cause 99% of the time we don't need that much data in vel field for mblur and they are pretty heavy. 25% res would suffice.

And one more thing - is there a control to change mblur settings - like backward-centerd-forward? found only shutter time. cause i noticed even when i managed to render my test volumes with mblur it still moves it a bit, but not knowing mblur settings i'm not sure if it's a bug or not.

Hi,

Nope sorry, I've double checked the Octane API, and in a volume object, all the grids must have the same resolution currently. About the motion blur settings, yes, currently the only parameter available is the shutter time, but in the volume objects, you can scale the velocity grid to control the volume blur, or even disable it if the scale is 0.

Hope it helps,
-Juanjo

[juanjgon]

UPDATE: not sure if my hip file uploaded - can't find where to look. is it possible to attach something but image at all?

You can attach .zip files, so if you need to upload something compress it first.

Thanks,
-Juanjo