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symek

Contour From A Geo

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I need to create a contour of my geo as curve or polygon. The same as I would render geo as constant surface and than trace it with TraceSOP. Due to some issues this substep would be extremely unconformable so I look for another way.

Tried to make it with raySOP but it doesn't work.

Any ideas?

thank you!

sy.

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I need to create a contour of my geo as curve or polygon. The same as I would render geo as constant surface and than trace it with TraceSOP. Due to some issues this substep would be extremely unconformable so I look for another way.

Tried to make it with raySOP but it doesn't work.

Any ideas?

thank you!

sy.

Do you know that you can perform that substep "automatically" utilizing the Render COP or the Geometry COP and Trace SOPing the result directly using the op:/ syntax?

I've done this exact thing you're talking about, btw - except I did go via disk. This is what I did:

*/ Render an image, exporting the Position of the sample; the "P" variable

*/ Trace this image with Trace SOP (+ grab the UV value)

*/ I used the BorderSOP (from the Exchange, I think) to shrink the contour a little. However, you might be able to get around this problem with other means, read on.

*/ Look up into the map again, using an UNFILTERED lookup (rawcolormap()) and...

*/ ..move the point to that position. This moves the silhouette to the point in space you're interested in. You'll have to parent this underneath your camera because the original P (that you exported from Mantra into the render) is in camera space, not true world space.

*/ Some points may be screwy and stuck at (0,0,0). Delete them procedurally.

The most annoying step is the Border SOP thing. At the time I was thinking of possibly writing a VEX routine that spiral out from given coordinates looking for the first non-zero sample and using that, but I ran out of time.

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You can make a border with the extrude sop too, that might work better than the vex border sop...

Just turn off all the generation of sides.

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Do you know that you can perform that substep "automatically" utilizing the Render COP or the Geometry COP and Trace SOPing the result directly using the op:/ syntax?

thank you Jason and sibarrick for your time. Yes, I know "op:/ " syntax. But the problem is that geometry begins from particles sim and what artist need to see during tweeking the simulation is a contour it self. So after every small change in sim an artist need to go through all steps to get contour as his visual feedback. That's why I was sceptical about subrendering stage.

I will try your advice.

thanks again.

sy.

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Czesc SYmek,

How about this:

Create a vop-sop which detects faces looking towards camera. Leave that faces and delete rest. Append a Divide SOP. Tick on the second option from the bottom "remove shared edges". Append carve SOP - this will leave you only a boundary edge. I think that is what you are looking for :)

I am sure I've done similar thing some time ago, let me have a look tmr, will send you if I find it.

pozdr,

kuba

Btw. how is Switez? Do you have any recent info about progress? Where and when can one watch results, there isn't any news on the website? Do you know anything about that? :)

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Depending on what you're doing, you might be able to extract the "equator" of the object by using the Group SOP's ability to group by Normal versus a camera angle. (GroupSOP>Normal>BackfaceFrom) - you can use two of these GroupSOPs and extract a narrow band around the object.

IIRC, I think there was another technique for doing this in the "hktoon" thing that Hwee Kok submitted to odforce a long time ago. Unfortunately the odforce database is under upgrade right now so I can't get at it.

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It's a pleasure to try all your advice guys :) I'm not sure about "toon" analogy as finally I'd like to stay in geo world - I'd like to finished with closed poligonal curve still able to tweak its shape.

Nice idea Kuba, I'll give it a try.

sy.

PS As to "Switez" I'm quite close to it right now. We have a hot time here. Lots of work is done in 2d but we still far away in 3d. Animation is almost finished.

What I can tell you that previews look more and more beautifully and I'm sure this gonna be a great pleasure to see it finished. There is a early screening in July in Warsaw with life orchestra but the movie won't be finished at that time. We try to make it as complete as possible until than.

Not sure if I can show something, but I'll ask... ;)

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PS As to "Switez" I'm quite close to it right now. We have a hot time here. Lots of work is done in 2d but we still far away in 3d. Animation is almost finished.

What I can tell you that previews look more and more beautifully and I'm sure this gonna be a great pleasure to see it finished. There is a early screening in July in Warsaw with life orchestra but the movie won't be finished at that time. We try to make it as complete as possible until than.

Not sure if I can show something, but I'll ask... ;)

Cool I'm waiting impatiently :)

and here is the file, hope it will help a little :unsure:

kuba

krawedz.hip

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