How to make separeted alpha maps ?

[bernhard]

Hello friends !

Well, I was looking for a solution to create seperated alpha maps - as instance if I do have a building, I would like to seperate the winows, from the frames, and the walls etc.

I've tried to render wireframes, but it's not antialiased, and it will not give me very fine results, even if I render in a igher resolution.

Is ther any special technique I can use for ?

thank you so much for every little help,
bernhard

[instinct]

http://www.chaosgroup.com/forum/phpB...ght=multimatte

We released one of our internal tools to do just that for free. It allows to create 3 Mattes per renderelement (rgb channels wich are easily seperable in post).

Regards,
Thorsten

P.S. it is already included in current betas and will be part of future VRay releases, so it's safe to use

[bernhard]

hmm..

thank you for this idea, I really would love to use this tool, so I 've downloaded it and I've copied the files into my vrayplugins folder.

But I get two error message:


Hmm, I use a Windows XP 64 Bit, but running 3dsmax9 32 bit on our system.

Hmm, any idea what's going on ?

thx a lot for every little help,
bernhard

[instinct]

well you installed the 64bit version. you need to use the 32bit one if you are using a 32bit max.

Regards,

Thorsten

[bernhard]

32-bit where to get ?

Hmm, well i've downloaded it from your website on www.mackevision.de
Ups, sorry, my fault, it has all versions included, so I need to use just one of these files...

now I have to make a test...
bernhard

[bernhard]

Test

Hello Thorsten and thank yu for your help.

I've made a quick test, and so far it works fine.
the only thing, I am a ittle bit confused is, what can I do, if I would like to use more than 3 objects ?

As instance, here a little test:
THE RGB


The 1st Multi:


2nd Multi render:


In this test scene, I do have 6 different objects. Now I would like to have 6 different colors. For each object, one different color. And, if possible all in one, at one layer... I mean, in one image.

Is there any way to do that ?

thx for every little help,
bernhard

p.s: by the way, I am from austria - so german native speaker too, but write english, so everybody else can read ....

[instinct]

Well, there is no way using Multimatte, but for a VERY good reason. you cannot really seperate colours other then Red, Blue and Green (you can simply use the Red Channel in PS and have a perfect mask, if it was purple for example you would have the object in both the blue and the red channel).

You can simply load the multiple images and seperate them as mask channels and combine them. The exact workflow depends on the software you use.

Regards,
Thorsten

[bernhard]

hmmm...

Hello Thorsten and thank you for your help.

I use 3dsmax9 and for stills photoshop.

So, there is no other way, I can select 3 different objects and seperate them with one render - is this correct ? And if I woul like to have more opjects, I need to change the object ID numbers - and render again, or ?

So you suggest, make all the renderings and seperate the objects like needed - after this, create different masks from the obejcts you do need.
Hmmm... I have to make some tests and see how it will work.

What I don't understand is, why I can't seperate other colors like red, blue or green in ps ? If I would have as instance, a yellow color, I could select this yellow color in photoshop too ... hmm, or did I missunderstand here something...


Now, I've made another test on a more complex scene file, and I have a little problem here. teh image I've got from the Multi Matte Render Element:



Well, it really looks weired, and the main problem is the antialiasing.

I did the same as before in my little test file with the box and sphere, but in this case - it's really different.

Is there anything else I have to think about ?

thx for every little help,
bernhard

[bernhard]

another test render

and here another test using a box, sphere and teapot in front of the bulding....

huuuuuu, what's going on here ?



bernhard

[dimo]

Hi,

first of all, the main idea is that you can take the different channels as mattes directly. So in Photoshop you could take the channels and turn them into a selection. The reason why this doesn't work with arbitrary colors is the anitaliasing. You will get wrong selections at the edges.
For example you have a red object a yellow object and a green object. The red object is in front of the green object. At the edges the antialiasing will mix the red and green. You will get yellow. But this is the third object. You can't do this.

What you can do is to add more than one multimatte renderelement. This way you can render out all the masks you need with one pass.

Your edges problem has probably the following reason:
The renderelements use the beauty pass for the sampling decisions. For example if you turn of your lights and render a black image and have adaptive sampling you will get poor antialiasing in the renderelements.

Easiest workaround for this is to tick the object outline checkbox in the adaptive sampler. This will sample the edges of objects in any case.

Hope this helps

Dieter

[bernhard]

wow...

Dieter - you are great, and you made my day.

This was the information I was searching for.
Everything works perfect now.

the only thing I am a little bit confused now, is the question about the resolution.

Here is my last test with you Multimatte:




As you can see, the model is more complex, with fine lines between the windows on the main glas front of the building.

The green parts of the mesh, are not really 100% to see - what can I do to avoid something like this ? I was thinking to multiply the render size 2 or 3 times, and after this scale it back to the original size.

But I am not sure if this is a good way...
any suggestions ?

Thank you so mch for your help and for this great tool.
bernhard

[3ddesign]

Look into PSD Manager. I use it and love it. Does exactly what you want.

http://www.cebas.com/products/produc...-33-788&PID=38

[dimo]

Hi,

Raise the min samples.

Best regards,

Dieter

[bernhard]

okay

Thx dieter, I think it worked now.

Really great tool, thank you for sharing with us, I really appreciate that.
bernhard