Selection based on image

[mabulazm]

Hi

is it possible to make a group selection based on image instead of geometry

cheers

[Andz]

Hi

is it possible to make a group selection based on image instead of geometry

cheers

I have used an image for selection, but the process was:

normal image --> black/white in COPS --> trace SOP --> extrude --> group selection

It is a geometry after all but I hope it helps.

[anim]

if you have correct uvs, then it's fastest and very simple in VOPs

just get your image (color map VOP)

get any channel or luma (luminance VOP)

test if it's greater than some treshold like 0.5

then add to point group inside if VOP

or if you are not into VOPs

create Cd attribute based on image (Attribute Create or Point SOP and tex() expression)

then in group SOP select by expression $CR>0.5 or so

group_by_image.hip

[mabulazm]

I have used an image for selection, but the process was:normal image --> black/white in COPS --> trace SOP --> extrude --> group selectionIt is a geometry after all but I hope it helps.

hey Andz

I though the same as you, a bit different but all go to same direction

if you have correct uvs, then it's fastest and very simple in VOPsjust get your image (color map VOP) get any channel or luma (luminance VOP)test if it's greater than some treshold like 0.5then add to point group inside if VOPor if you are not into VOPscreate Cd attribute based on image (Attribute Create or Point SOP and tex() expression)then in group SOP select by expression $CR>0.5 or so

hey

thanx a lot, this is exactly what i want to do, just had a look in the VOP, it looks easy to understand.

so the idea is create a global with world image, then make this image to be a selection group to copy a sphere for example.

i will give it a try.

could you tell me from where you got the Group Name parameter ... could not find it inside the VOP

Edited November 10, 2010 by mabulazm

[Andz]

hey Andz

I though the same as you, a bit different but all go to same direction

Yeah, I went that way because i needed a volume selection, not just a surface. I actually had 3 different images (top, side and front views).

Like a "poor man's 3d scanner".

Edited November 10, 2010 by Andz

[anim]

that works for 3d selection too since projection works in any depth

just make 3 projections or more with different images and multiply the color result then select group by treshold

[Andz]

that works for 3d selection too since projection works in any depth

just make 3 projections or more with different images and multiply the color result then select group by treshold

Thanks for the tip, I'll take a look at that file ;-)

[mabulazm]

that works for 3d selection too since projection works in any depth

just make 3 projections or more with different images and multiply the color result then select group by treshold

ummmm , am not that expert

so if you have time to make a quick example for me will be great, specially with a sphere

cheers

[anim]

ummmm , am not that expert

so if you have time to make a quick example for me will be great, specially with a sphere

cheers

sure, here it is

i've made a little more universal nodes so you can use them for other ways if you want

group_by_color.hip