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Old 20th July 2012, 12:42 AM   #1
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Default Define Seams for LSCM Mapping

Since AC3D doesn't have edge select support, would it be possible for the next version to allow you to define seams by selecting vertices?

LSCM mapping is a real pain otherwise, because you either have to unweld and then weld the vertices or you have to stretch and resize each section you map (Unless I'm missing something...).
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Old 20th July 2012, 11:34 AM   #2
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Default Re: Define Seams for LSCM Mapping

All that unwelding and welding isn't really necessary.

What I normally do to set up a texture map for a (fairly) complex object:

1) In one viewport, create a square or rectangle ( square if I need to create a perfectly square-dimensioned texture map); make sure it's big enough to visually give you room to place objects. Move it a considerable distance away from the model in any viewport, and offset it so you can avoid confusion later as you work with parts and copies of parts. Lock it (so you can see it but not select it). Enter wireframe mode.

2) Select a major part of my model; in my case, I'm building aircraft, so I'd select the fuselage or a wing as a "major" part. COPY it. (The idea is to leave the original model untouched, so as not to mistakenly ruin it while doing mapping).

3) Paste the copy and move it up "into" the locked rectangle. Rescale it to take up as much or as little space on the texture map as it "deserves"; in my example, the wings and fuselage would take up large %s of space, the inside of the wing root I would shrink down and wedge into space between major objects. Any objects that are to be contiguous, or that get a lot of visual scrutiny, I would scale them the same degree, to make things easier when painting. For example, I would not split up the top and bottom of a wing and size them differently.

To help in this process, I may need to move the copied parts "forward or backward" so that they can be seen "in front" of the guide rectangle, if I need to work outside of wireframe mode.

4) For surfaces that need to be rotated on axis or tilted for a more direct "camera angle", I would select the surfaces and Cut Away Object. Then, move, rotate or otherwise manipulate so as to preserve surface sides that should mate on "seams". There's no real need to "weld" the common vertices together. They just need to appear as "flat" as possible against the rectangle in the viewport you're using for the sizing rectangle to face.

5) Repeat 2-4 for all parts of the model. After you do this for a short time, you'll get used to detaching and reorienting faces for "box" shaped objects, globes, etc.

6) Once you've created and positioned all the shapes in your rectangle, go full screen for the viewport you've created the rectangle in; zoom in your viewport until you can just barely see the sides of the rectangle. Enter whatever mode best suits you for making a graphics guide (for example, I leave wireframe mode, so that surface edges are visible on my guide, which may help me while painting). You may need to move objects that are "behind" the sizing rectangle, and thus won't appear on the guide. Then take a screen grab of the rectangle area (and all the parts in front of it) using Clipping Tool, SnagIt, or whatever screengrab utility you may have. Take care to take a perfectly square grab. Eventually, you'll resize that screengrab to 1024 x 1024, or whatever "power of 2" size you need to work with.

After creating my guide, I usually try and get into Photoshop and create a guide layer with text to describe all the shapes, so I don't forget later. Also place any notes about orientation (e.g., this side faces forward on this part, or "this square-shaped surface is the front of a box-shaped object, this one is the left side" or which wing is port and which is starboard, which are the tops of the wings, which are bottoms, etc.
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Old 20th July 2012, 04:11 PM   #3
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Default Re: Define Seams for LSCM Mapping

Thank you very much for the detailed tutorial, that sounds like it might be a much better method than what I was doing for that type of model (leaving the model alone and mapping/painting one set of faces at a time). The only thing that I don't really understand is how you set the UVs on the original model -- unless I'm missing something major it looks like you'd have to go back and re-map each face.

I don't really have too much trouble mapping simple (and not so simple) things like cars or airplanes with the existing tools, the only thing I'd love to use LSCM mapping for is character faces. Being able to set a seam on the back and sides of a head would make it a lot easier for me to map the face (although maybe my problem is just because that's how I learned to do it in Blender).

Additionally, the existing LSCM implementation seems slightly "off" from what I'm used to. In Blender, this unwraps symmetrically while in AC3D it looks a little wonky.

Last edited by Noob; 20th July 2012 at 04:29 PM. Reason: Added additional information.
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Old 20th July 2012, 05:40 PM   #4
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Default Re: Define Seams for LSCM Mapping

Well, if you create the guide, and leave the surface division lines on it, then you can go right to the TCE and "texture" the model such that all those surface lines match up with the model. Here is where you can use "snap together" to seamlessly mate any vertice groups that might get separated by your breaking up the model.

Then, as you paint the actual guide graphic, you can then just reassign the whole model to use the copy (the painted texture or textures if you require more than one) and it will all stay assigned properly.
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Old 20th July 2012, 08:06 PM   #5
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Default Re: Define Seams for LSCM Mapping

Okay, that makes a lot of sense. The way I was doing it could get me into trouble if I didn't allocate enough space for all of the faces I wanted mapped.


Regarding the LSCM mapping disparity between AC3D and Blender, do you think I should make a separate post about that in the bugs forum? I'm not really sure if it counts as a bug or not...
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Old 20th July 2012, 09:58 PM   #6
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Default Re: Define Seams for LSCM Mapping

To be honest, i don't know enough about other mapping processes to comment on it.
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Old 21st July 2012, 03:05 AM   #7
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Default Re: Define Seams for LSCM Mapping

Okay, then I guess I'll try some other 3d programs to see if AC3D's LSCM unwrap method is standard and make a post in the bugs forum if it isn't.

Thanks again for all your help!
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Old 21st July 2012, 09:38 AM   #8
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Default Re: Define Seams for LSCM Mapping

It would be awesome, if we could have an instance model, which would be a copy of the original that could be taken apart, rotated and sized. And the original would be textured automatically.
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Old 21st July 2012, 11:46 AM   #9
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Default Re: Define Seams for LSCM Mapping

I believe you already CAN do that, by making the copy an instance, however, it's a case of "chicken or the egg"; what do you texture the original with, if the purpose of creating the instance is to create the texture guide? And you certainly wouldn't want to try to recreate the original from the cut-up model flue copies!!
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