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Old 10-13-2012, 07:09 PM   #31
helluvapixel
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Troyan,

If it works for you then that's awesome. I'm not posting to tell you or anyone they are wrong. I've dealt with CAD conversions for many years and I am sharing what works for me, and some of the pitfalls that arise with different formats.

I tend to work more on commercial products where maintaining the CAD shape and shading model is important. A format like STL does not support vertex normals, so I lose geometry shading information there. When you start messing with phong angles you start changing the topology shading; what should have been a tight edge isn't so much any more.

In many cases, the files I receive from clients are of prototype products under development. Not maintaining hierarchy becomes a headache when you have to cope with product definition changes or making product option switches.

In regards to PolyTrans failing you, that you have to take up with Okino.

Out of curiosity, what is the price of Transmagic? and are you using it to convert only STEP or native CAD file formats?

For anyone that's interested my workflow is such:
  • Recieve the CAD file. I request native file if I can support it, or STEP 214
  • I load CAD data to Creo (Pro/ENGINEER) and review content and strip out model information not required. I'll also clean up bad surfaces, trim surfaces etc. If it is a large assembly I'll parse it for subassembly conversions.
  • I'll feed cleased or supplied model to PolyTrans (or modo) and apply the mesh conversion and tessellation. This step may iterate a few times to get the right mesh density ratio.
  • I will save a PolyTrans file. I will then clean up the hierarchy for a more animation friendly organization.
  • I'll review key parts and remesh components that need less/more mesh density.
  • For Cinema 4D, I'll export a Collada file. I'll use FBX where requested or other formats.
 
Old 10-13-2012, 08:03 PM   #32
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Quote:
Originally Posted by helluvapixel
Troyan,

If it works for you then that's awesome. I'm not posting to tell you or anyone they are wrong. I've dealt with CAD conversions for many years and I am sharing what works for me, and some of the pitfalls that arise with different formats.

I tend to work more on commercial products where maintaining the CAD shape and shading model is important. A format like STL does not support vertex normals, so I lose geometry shading information there. When you start messing with phong angles you start changing the topology shading; what should have been a tight edge isn't so much any more.

In many cases, the files I receive from clients are of prototype products under development. Not maintaining hierarchy becomes a headache when you have to cope with product definition changes or making product option switches.

In regards to PolyTrans failing you, that you have to take up with Okino.

Out of curiosity, what is the price of Transmagic? and are you using it to convert only STEP or native CAD file formats?

For anyone that's interested my workflow is such:
  • Recieve the CAD file. I request native file if I can support it, or STEP 214
  • I load CAD data to Creo (Pro/ENGINEER) and review content and strip out model information not required. I'll also clean up bad surfaces, trim surfaces etc. If it is a large assembly I'll parse it for subassembly conversions.
  • I'll feed cleased or supplied model to PolyTrans (or modo) and apply the mesh conversion and tessellation. This step may iterate a few times to get the right mesh density ratio.
  • I will save a PolyTrans file. I will then clean up the hierarchy for a more animation friendly organization.
  • I'll review key parts and remesh components that need less/more mesh density.
  • For Cinema 4D, I'll export a Collada file. I'll use FBX where requested or other formats.


No, I'm not saying I'm right and you're wrong, I'm saying I'm not seeing the issues you laid out. Your workflow works great for you but it's way overkill for most of the CAD conversion that needs to happen in this community. I'm sure you're right about running into issues with tight corners and vertex normals, but what I'm saying is this solution is far faster, easier and I'm not seeing the issues you're pointing out. Technically, I'm sure you're correct, but what matters is what happens when you render, and what you're saying has not been my experience. I'm not seeing any loss in geometry shading, tight edge or otherwise. Did you see that cannulated screw in that shot? There's a lot of tight edges there. Is there an issue that I'm missing? Here's my steps.

1) Get STEP 214 from client
2) Drop onto Transmagic. Transmagic evaluates all of the edges and angles and creates the best triangle mesh to produce a clean result.
3) Save out as STL
4) Open in cinema, drop on a phong tag and adjust the phong angle to taste.

That's it. Everything is nice and smooth and shading correctly and I'm done in minutes. If people are unhappy with this solution, then by all means they should follow your steps.

Btw, when Polytrans failed us, we did take it up with Okino and it wasn't pleasant. It basically came down to a long dissertation on how Okino was the best and it was the fault of the CAD creator, the formats and us. Then we tried Transmagic and haven't had to deal with that ugliness anymore. Transmagic's customer service has greatly improved as well. When we had a question on a feature one of their developers recorded a Camtasia on exactly how to use that feature based on a model I sent him. A refreshing contrast to a long email about how much we and everyone sucks.

I've been doing this for 12 years of literally tens of thousands of conversions trying Rhino, Moi, Viacad, Okino and a slew of other forgotten solutions. What matters in the end is speed and how it looks when it renders and, until something better comes along, this is it. Technically, I'm sure your approach creates the best, purest result. But, again, I think it's overkill.
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Old 10-14-2012, 12:45 AM   #33
helluvapixel
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Jason Clark
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Quote:
Originally Posted by Troyan
Your workflow works great for you but it's way overkill for most of the CAD conversion that needs to happen in this community.

Your contrast in method is appreciated. Your rendered exampled would completely fit your workflow and I would do the same.

Quote:
Originally Posted by Troyan
Btw, when Polytrans failed us, we did take it up with Okino and it wasn't pleasant. It basically came down to a long dissertation on how Okino was the best and it was the fault of the CAD creator, the formats and us.

I won't argue you there, I know of what you speak

Good discussion.
 
Old 10-14-2012, 12:46 AM   #34
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