Texel dialog
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I looked up texel on wikipedia: http://en.wikipedia.org/wiki/Texel_%28graphics%29
Didn't make me much wiser - seemed rather vague...As for your request: is it info on how many times a texture repeats across a surface?
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This is my understanding of what he is looking for:
I think it is more like pixels per mm (or meter or whatever your brain thinks in, for me its inches
). And that is not mm in screen space, but mm in model space.So your textures should all be about uniform pixels per cm. Maybe you decide 1 pixel per cm. Then you would know that a wall that is 1m tall would need to be made at 100 pixels in height. And then calculate your entire model like that. Its a way of ensuring that little postage stamp size faces do not have 2048 x 2048 pixel images applied to them and large building facade faces do not have 64 x 64 pixel images.
That is my understanding of it all, so forgive me if I'm wrong. I think it is scriptable.
Chris
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You got it -- it's the pixel density. So a 1:1 texel ratio would be 1 pixel per 1 unit on the model. So a 256x256 texture at 1:1 would fit exactly on a 256 unit wall (before repeating).
This means you could swap the 256x256 texture for 64x64 and you'd see it repeating 4x on the wall.
This wouldn't be the Texture width/height in the Material browser, correct? That affects the individual texture and how it's applied to anything in the world. The texel concept is scale applied to the UVs of the object.
I'm still wrapping my head around this concept. It seems simple, but I suppose it's confusing at first because I haven't seen a dialog for it readily exposed in any major editor [Max, Maya, SketchUp] (so it's not easy to play around with).
--alz
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alz, Sketchup handles textures in a different (I think better) way to most modellers.
The short answer, is that Sketchup does what you want 'right out of the box' because for each texture, you specify how much world space it should cover. Sketchup then ensures that the texture repeats sufficiently to satisfy that "texel density".
Just open the material editor and change the Width/Height fields which are World Units (eg meters / feet).
My plugin called Goldilocks uses the Sketchup material "texel:world space density" to check whether for a given viewpoint, that density gives a good "texel:pixel density".
In other words, Sketchup will automatically texture like your second image.
Adam
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Thanks for the explanation Adam!
I suspected this was the case, but was unsure. I didn't know if Texel information was part of the object (meaning you could toss whatever texture you want on it and it'd match the ratio) or if it needs to be specified for each material.
SketchUp far more simple and to-the-point than massive programs like 3dsMax!
--alz
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Here's a follow-up question --
Let's say I have 10 textures. 1 is 512x512 in resolution, set to 512x512 sketchup units. The other 9 are 256x256 in resolution, set to 256x256 sketchup units.
By default, applying all these textures on different sized faces will produce a 1:1 texel ratio.
So...
How would I make everything 4:1? Would I have to go in to Texture/Position and scale every face?*** Or, is there an option or plugin that can pick the desired scale from a face and transfer it to other faces?***Texture scaling doesn't have a VCB numeric option for exact sizing? And without a way to display the current scale, there's no way to understand what the current texel ratio is, correct? I wish the "Reset Position" option was actually three options: Reset Position, Scale, or Rotation.
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The easiest way to recale so a 1:1 up to 4:1 would be to go into the material browser and just change the dimensions of the material. To get 4 times better texel resolution, change the 512" x 512" to 128" x 128". Then you have 4 pixels per inch in your model. And it will resize the faces accordingly.
It will not reset the existing scale applied to any specific face though. But it will multiply on top of that scale. Try it out by making a bunch of faces, add the default scaled material to them. THen change the scale manually on a few of the faces. THen go into the in-model materials and edit the material. You will see how it changes on the default faces and on the faces where the mateerial was manually scaled.
Hope that helps,
Chris
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Ah -- yeah I can see what's happening. Thanks for confirming Chris!
In large scenes, it'd be easier if there was a global setting or way to transfer one scale to another. If there's 20 or so textures in a scene, that's a lot of material changes to do, heh.
For example, you might want to keep the default size for 80% of faces that use the material, but on the other 20% you want a different density. So instead of duplicating the material to change the scale, find a way to simply change the UV scale on the 20%.
I'll poke around the web and see if there's something already out there. If not -- maybe it's a good candidate for a plugin.
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On a side note, I am realizing my math is sloppy, or possibly mis-leading too.
512x512 image at 512"x512" is 1:1.
To get to 4:1, if you mean 4 pixels to one square inch, then you actually reduce 512"x512" to 256"x256". That will produce 4 pixels to one square inch. going to 128"x128" will produce 16:1 - 16 pixels per square inch.
So don't mess up your math like I did, or you will end up with overly detailed or incorrectly scaled images.
Chris
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haha -- yes -- good point! I had forgotten about the squared aspect as well
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