Ahh thanks both! That's perfect!
I came close to your method mestela but got confused when the resample copied my attribute to all the new points and missed the all important attribtransfer step!

Tamte> wow. That's truly elegant!

I have a curve with a few points, (group1)
I resample the curve using the resample by polygon edge setting and a fixed distance between points, (group2)

I would now like to delete those points which were in the original curve.
Since each line section of the curve may be a different length, there doesn't seem to be an expression I can use to group and delete these points.

Please someone tell me how can I delete the points from group2 which are also in group1? I can't figure how to do this with the delete, group or blast nodes but I feel I'm overlooking something simple..

thanks all!

Wow, that's spot on! thanks mestela!

That's the best title I could think of to describe what I'd like to do.

I have an enormous piece of geometry onto which I'd like to scatter points so I can point instance plants from them for my forest. The geo really is too big to comfortable scatter all the points on the entire geo and the render time was too long anyway, so I set about thinking of a ‘cheat’.
I think if I use a backdrop texture and only render plants close to the camera, I can get the effect I want. I can create a bounding sphere around the camera, crop out the local geo, and then use that for the scatter. So far, so good.
But this idea fails when I move the camera (ultimately I'd like to fly over the landscape) because the cropped geo will generate a different random scatter for each frame.

Is there a way to solve this? or is my plan flawed? maybe there's a better method someone can suggest me?
Any help gratefully received!

That works quite well actually - thanks blackpixel! Gives me an excuse to learn more uses for loops too!

I'm trying to teach myself more about procedural textures/materials. whilst there are quite a few good tutorials out there which help with subjects such as rocks, I'm having less luck with generating noise that looks like ‘sticks’, ie. isolated lines in random orientations.
This would form the basis of straw, grass, dirt and similar procedural debris materials.
Any tutorials or pointers from others? Best idea I've got so far is based on worley noise but I'm not sure how to shape it.

Attached an image which I'm aspiring to recreate in Houdini.

PS. I know about geometry and fur procedural methods for grass - but I'm looking for a procedural material here for learning purposes.

Thanks all!

That looks to be spot on, thanks eetu!
and I learned yet another new way to do things in houdini - awesome

Ahh, thanks! so I'm approaching the problem wrongly

Sorry to sound like a noob but mantra is usually the last node in my workflow - I get that I can set P as an export plane and hence get Px,Py,Pz, but how do I then get to my desired final output (I'm after a 16-bit integer single channel png where each pixel is the distance from camera to the surface)?
Are there any example files I can learn from here?

Thanks Joker!
I've modified the file so it shows the problem - the only changes I made were to switch off the plane object and move cam1 to the origin. We're now inside the unit sphere you made.
When I render now I get the attached image - I can't even save this out as a png since the right hand side (black) is actually very negative, so here's a screenshot.
If we're at the center of a unit sphere, shouldn't all pixels be a constant value?

I can't seem to find the answer to this and my head is hurting, so perhaps someone could please explain..?

If I create a camera and sphere at the origin, set the camera to render a polar projection and add an extra image plane, Pz… shouldn't I expect to see the render filled with a constant color?

Isn't Pz the distance of a point to the camera (which is also a point)?

If not.. how do I go about rendering a depth map in polar mode? (I could achieve this using a custom shader, but that means overriding the shaders already applied to my geo which is no good)