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Texture Atlas - a very useful add-on for Blender


Dree Eames
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The Texture Atlas  http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/UV/TextureAtlas  * add-on is very handy and looks much more intimidating then it really is.  With this add-on:

1) You can quickly and conveniently associate multiple objects to a single texture for baking. Within the add-on you can set the resolution you desire for the texture as well as the option to automatically uv the selected objects, or you can manually set up your uvs on a merged duplicate, or you can just keep the UV positions already created. For manual work within the plug-in and select  “Start Manual Unwrap” to create a merged proxie , and then "Finish Manual Unwrap"  unmerges it  back to seperate objects with the new UVs (if changed) and all objects associated linked to a single texture for baking.

- And -

2) You can use the add-on  to combine many objects into a single object and end up with a single UV set where all the uv positions remain in place.  The plug in automatically removes the original UV sets. Basically you create the merged duplicate I mentioned above and you don’t unmerge it:

Select the objects you wish to combine.
In the Texture Atlas Subpalette press the plus sign to create a group from the selected objects .  You can give it a new name or accept the one given. 
Select:  "NO UNWRAP"  and
Select: "START MANUAL UNWRAP"

A merged duplicate of your selected objects will appear in the 3d scene and in the item list.  The original objects you merged will be in the items list set to hidden visibility.  The original objects can be deleted or saved to another layer.  

Again, this merged object duplicate you create will have a single UV set- all the uvs islands remain in their original positions and the original uv set names/versions will have been deleted.

I had to watch numerous youtube video tutorials to get the hang of this plug-in and get a good understanding of it's features.  I find it very useful.

(Warning: Please note that in one tutorial I watched via Youtube - https://www.youtube.com/watch?v=XO9gOeDcgzg - the instructor demonstrates a highly convoluted and unnecessary "work-around" for using this add-on when baking in cycles. This unnecessary workflow could discourage beginners to Blender from bothering with the add-on. His method is far more complicated then is necessary and quite frankly one can simply associate multiple objects to a single texture manually much faster then his “fix”. His method of copying and deleting materials is simply NOT necessary to bake in cycles.  I'm not sure if he ran into a bug in an earlier version of Blender or simply had a midunderstanding of how to use this add-on. I tested the add-on using multiple materials on multiple objects and using the Texture Atlas add on and I had no trouble using cycles to bake in a straight forward manner as with the default Blender Render bake.)

*Edited to correct error in wiki blender link at the top of the post.

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Interesting post. Thanks for sharing, Dree. You are right when you say the tool is intimidating. I tried to get the hang of it a couple of times and never figured it out. I need to look into this again. Is there any tutorial you could suggest?

I have shared your post through my social accounts. Some people will find this interesting.

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I'll try to put together something to explain how it works and post it here in a day or two.  The add-on is a lot like Blender in general.  Very scary "off-putting" terminology", but a piece of cake once you get used to it!  I hope you find it usefu!

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<waves at Dree>

It sounds interesting and I will take your word for it that it is a handy thing, but no one here will be surprised to hear that I did not understand why :-D  (Without you and others here I would still be trying to work through a beginning Blender tutorial.)

I will look forward to your future posts on the subject!

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 /me waves back!

Here it is :):

 

The main purpose for the Texture Atlas add-on is to aid in baking an ambient occlusion texture/lightmap using groups of objects in a scene baked down to one texture.   AO doesn’t require a high resolution texture, so makes sense to  gang many objects together and baking ao to a single texture - useful in many game environments.  For Second Life there are other uses we can find for the plug-in since it allows us to create uv sets with the same name across a group of objects and also it offers the option to delete any prior uvs sets associated with these objects so you are left with a single UV set per object.  This is very handy for SL as when uploading as you can only have one UV set per object - you must delete any extra uv sets.  And with all the uv set names consistent you can join and seperate objects at will without destroying the  existing UVs.  Also, there are many situations where you might want to set up a single bake texture that includes multiple objects.  

 

The Texture Atlas add-on creates a single  texture, automatically links all the UV sets for a set of grouped objects to that texture for baking purposes, and it quickly and easily and creates UV sets so there will be no overlap when baking.

 

The Texture Atlas add-on sub-palette exists in the Render palette.  To use it, first select the objects you want to “combine bake” together into a single texture then press the plus sign:

Screen Shot 2015-03-10 at 6.01.10 PM.png

 

 

By pressing the plus sign you create a group from your selected objects and the menu opens up to provide a bunch of options.  You can accept the default name for the group or add your own group name.  This name will appear both on the texture that the add-on creates and links to the objects and for all the UV sets created with the add-on.

 

You can see that you have an option to set the bake texture Resolution. Left is the X resolution and Right is the Y resolution.  Your bake texture doesn’t have to be square, but it should be based on the usual power of two in both directions.

  

 

Remove Other UVs:   

 

For objects that already have a uv set, this button optionally deletes any original uv set(s) and leave only the new one created here within the Texture Atlas palette.  Once the prior uv sets are deleted every object in the group will have a single UV set with the same group name.  This facilitiates combining objects together (ctl J) into a single object if need be.  As we know from prior forum threads, if you try to combine objects that have different uv set names it screws up your uvs.  Although you can rename your uv set’s manually, it’s tedious stuff.  This is more convenient and fixes all the objects in the group in one go.

 

Remove Selected:

 

This removes a selected object from the group you created.

 

Add Selected:

 

This adds a selected object to the group you created.

 

Select Group:

 

Similar to the select option in the Vertex Groups and Materials palettes menus this is simply a select button. It highlight/selects all objects in the group in the 3d edit window.

 

Auto Unwrap:

 

Here is offered two of the same options from the default UV unwrap menu: Smart UV Project and Lightmap Pack. Select the type of unwrap you want by highlighting  Smart_Unwrap, Lightmap or No_Unwrap.  Then press Auto Unwrap.   Two things happen.  A bake texture (texture grid style) is created and given the same name as the group name.   Secondly UV sets are created for each object and given the same name (the group name) and, except for the No_Unwrap option, the objects' uvs are arranged in UV space as if all the objects were combined into a single object and unwrapped - that is their uvs are arranged so there is no overlap when they are all  baked together to this texture.  Again, all the linking of each objects UV set  to this  texture  happens automatically. Very convenient.  

 

You would select No_Unwrap if you’ve previously unwrapped the object(s) and only want to create a bake texture and associate the objects' UVs to the texture for baking.  With the No Unwrap option, the uv’s that already exist are duplicated and the second set is given the group name.  Select the objects and press RemoveOtherUVs to delete the originals.  If after using the No_Unwrap option the UVs overlap and create problems with baking you can simply join the objects together temporarily in the edit window (ctrl J) and rearrange the UV islands, then select each part that should be it’s own object and press P to seperate it.

 

The number slider to the right appears to set the amount of empty space between the created UV islands.  0.03 seems about right.

 

 

Manual Unwrap:

 

This option is interesting.  When you select StartManual Unwrap a single “Proxy” object is created made up of all the objects in the group.  This proxy object appears in the 3d view and in the item list it appears as TextureAtlas_mergedObject. The the original seperate objects are hidden.  Using this joined up proxy you can edit all the UVs together and when done you select Finish Manual Unwrap and the proxy object disappears leaving you with the original objects in the group visible.  These seperate objects will have inherited the uvs you manually created and each will have a uv set with the same name.  And again, they will all be linked to the same texture for baking.

 

Screen Shot 2015-03-10 at 6.50.08 PM.png

 

 

I hope I clarified things here and not have made it as clear as mud.  It’s really a very simple menu when you understand what each setting does - and it’s a very nice convenience!

Edited to correct many typo errors...although I'm sure I've missed quite of few.

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