Hi all ,

In the help for the volumesmoothsample vex function, there are two images that show interpolated fields based on a series of known positions. I was hoping to extrapolate this to generating a heightfield via a wrangle where the sample points are fed into the second input. What trips me up is that I would expect it to need multiple input points to find the weighting and 2d position to sample from but you're always sampling a known P + an offset because you don't want to same @P directly otherwise you'll return the heighfields value at that location.

Hi,

The smooth interpolation is used to interpolate between the voxels when sampling a single position, not to interpolate between multiple arbitrary positions from the field.

I'm sorry, smoothsample? did they add some cubic or catmull thing for volume sampling?

Many thanks for the reply. Fortunately I'm working through your excellent Pragmatic VEX series as I thought it might be the case, that it wasn't going to work; so my guess is I will be looking to extrapolate point based interpolation from 1D to 2D so I'll need four reference sample points rather than two. I don't suppose you would have any tips for getting started on that please ?

zampha
Many thanks for the reply. Fortunately I'm working through your excellent Pragmatic VEX series as I thought it might be the case, that it wasn't going to work; so my guess is I will be looking to extrapolate point based interpolation from 1D to 2D so I'll need four reference sample points rather than two. I don't suppose you would have any tips for getting started on that please ?

Thanks a lot for your words For this I would use the spline function:
https://www.sidefx.com/docs/houdini/vex/functions/spline.html [www.sidefx.com]

It supports various interpolations like linear, cubic (Catmull-Rom), K-Spline, Bezier/B-Spline/Hermite. I will probably cover these in Volume 2.

jsmack
I'm sorry, smoothsample? did they add some cubic or catmull thing for volume sampling?

https://www.sidefx.com/docs/houdini/vex/functions/volumesmoothsample.html [www.sidefx.com]
https://www.sidefx.com/docs/houdini/vex/functions/volumecubicsample.html [www.sidefx.com]

https://www.sidefx.com/docs/houdini/vex/functions/volumesmoothsamplev.html [www.sidefx.com]
https://www.sidefx.com/docs/houdini/vex/functions/volumecubicsamplev.html [www.sidefx.com]

Ah, thank you I didn't know that function even existed, time for some experiments. I look forward to volume 2.