hi everyone.
i want to create a group of points that i view in each frame or a group of points that are in front of camera.

does Houdini have a tools or trick to do that?

you can use the uvtexture sop to project a uvset from the camera.

- “perspective from camera”
- select your cam

in a group sop select group ‘by expression’

$MAPU >= 0 && $MAPU <= 1 && $MAPV >=0 && $MAPV <= 1

Best,

G

that's nice, but has a problem.

points that are in back of the camera, selected too :shock:

like this :

http://www.freeimagehosting.net/image.php?57c27dc12b.jpg [freeimagehosting.net]

This expression works:

$MAPU>0&&$MAPU<1 && $MAPV>0&&$MAPV<1 && $MAPW>0&&$MAPW<1

You also have to manage the w depth component (which is “real” handy btw).

Make sure that the UV Texture SOP is set to point mode and the same for the Group SOP that this expression is being typed in to.

All the points in the camera frustrum should be picked up with this expression. Try feeding in a box SOP with a lot of divisions.

thanks jeff and keyframe.

Thank You Guys

There my Version Selection Points From Camera for Houdini 17 + Promotion for Primitives and Colorize