subdividing for displacement

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SandroS
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hopefully the images will explain:

here is a simple plane, duplicated 4 times. as you can see in i have pre-subdivided some of them in my modelling app. the finer the detail you want, the more subdivision you need. this can be done in Thea also but if you presubdivide like this into roughly equal spacing, you will get a better result.

Image

in Thea the planes will look identical as Thea doesn't show edges that are planar. this keeps the openGL viewport tidy. i have applied a simple checker procedural. the first image shows the effect of displacement with no further subdivision in Thea. as you can see, the top left plane is still flat. this is because it is a single poly and has not been subdivided. even the bottom right plane, displacement is only just coming through. as a rule of thumb the plane needs to be subdivided to the size of the smallest details in your map. as you can see, the more subdivision the better the result, but as always it comes at a price. more polys usually = heavier scenes and probable longer render times.

in Thea with no subdivision applied:

Image

now with Thea subdivision level 2 applied:

Image

subdivision level 4:

Image

and 6:

Image
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SandroS
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joe average wrote:Nice Materials Wax. I've got a couple of questions though. Sorry if this is OT but here goes:

1) So if i set subdivisions to a greater no. in thea i need not subdivide in the modeling app? And the only way to know how much to subdivide is trial and error?

2) If subdivision is done in case of displacement mapping it must also be needed in case i need to just use bump and not displacement. In that case it probably needs to be done in the modeling app and cannot be done in thea?
1) it's not pure trial and error. basically, every time you subdivide you are cutting the poly in half. you can eyeball how many times you will need to cut if you look at the original mesh.

failing that use IR :). activate IR, move the camera close to the object and see how it looks. hide everything else for quicker feedback (you can temporarily move the object to a new layer for this). start low and only increase to what you need for your details.

2) as far as i know Bump doesn't require the same treatment.
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joe average
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Thanks for your reply SandroS... That means bump works without any subdivisions..? I'll try it out...:) :thumbup:
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warnotte
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Yes, bump doesn't involve any subdivision. It's all question of "light shaders". Very fast method that can give a very good illusion in a lot of case.
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SandroS
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and don't forget normal maps. in some situations, they give a much better result than bump mapping can, without the overhead that displacement requires. for example the other day i was making a tile material but couldn't get enough bump on my grout lines with a bump map (or bump maps with lots of straight edges). on Greenuser's suggestion i tried normal mapping and it worked a treat. if i find some time i will post an example.

in the mean time, HERE is a simple PS plugin filter to convert your bump maps into normal maps.
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nigec
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you can also create normal maps in Thea
http://nigecstudios.co.uk/?wiki=normal- ... p-and-thea
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Hieru
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There's also nDo for Photoshop which offers a bit more control over the creation of normals.
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joe average
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Thanks guys :)
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KarinaGM
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I haven't been able to make nDo work. That, or I'm making something wrong.
May it be something to do with my graphic card or something? I generate it without touching everything (and with the same valuse I see in the image of the tut) and I don't see a blue/magenta image, but a white/light blue version of my original. No matter what image I use as a base and if I grayscaled before.

Hints, please?
maderaBarra.jpg
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Hieru
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I did get a result like that once and my display driver crashed at the same time. I just updated my driver and haven't had any problems since.
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