Transparency map bug?

R

Ricardo

0
Transparency map bug?

Hello Cheetah community,

I was wondering if anyone else is having this problem. When I map a texture that has a transparency map on an object (flat plane) it causes artifacts on other geometry's texture that are behind that transparency. The problem gets worse as the texture on the other object is scaled wih the UV coordinates. I've included these images to illustrate what I mean. You have it with and with out the transparency map object to compare. Operator error or bug? Thanks for any responses.

-Ricardo

001.jpg

002.jpg

003.jpg

004.jpg

005.jpg
 
Hi,
you are right that doesn't look to good. :oops: Sorry.

The problem is that Cheetah3D just uses anisotropic texture filtering for the primary rays. But for rays that are reflected or rays that are transmitted through a object is uses just bilinear texture filtering. So the texture behind the transparent plane won't be filtered anisotropically.

Now you see the difference between anisotropic and bilinear texture filtering. Which isn't very nice of course. :cry:

I will try to find a solution for that problem. I've put it onto my todo list.

Sorry that I can't offer an immediate solution.

By,
Martin
 
Martin, if you're looking into transparancy etc. Could you also fix the shadows that don't appear through an object with alpha mapping. The shadow has the shape of the plane instead of a leaf pattern (for example). This would be great so I can make large amounts of trees that also have the right shadow. Maybe it's possible to add your own transparency map (just like the reflective, spec, bump and so on). Anyway you allready have a lot on your TODO list (I hope this is one of them) :p

Regards,
Peter
 
alpha shadows

Hi Peer,

I think you can do this already (it works for me). You have to make sure to turn on "raytrace+transparency" in the shadow under the light tag.

-Ricardo

shadow.jpg
 
Same issue with HDRI?

Hi Martin,

Thank you so much for the quick reply. I was wondering if the issue illustrated below with HDRI is the same thing. As you can see we are still getting those artifacts in the transparency (looks more wash out than artifacts) but the main problem is that when I render in HDRI with out the background the background is still seen in the transparency of the object where it doesn't cross any other geometry. Thanks!

-Ricardo

hdri01.jpg

hdri02.jpg
 
introductions

Hello all,

I kind of jumped into this forum with this topic with out a proper introduction and why I'm using Cheetah3D. First of all hats off to you Martin. I am simply amazed at your work. It's rock solid, intuitive, easy and fun to use. I found out about Cheetah3D through a review in MacAddict (4 out 5 stars only because they felt the documentation wasn't complete) download it the demo and within ten minutes I had placed my order.

The reason why I got Cheetah was because I'm redoing my patio and my contracctor could not visualize the idea I had for it. I'm not a 3D guy (I'm actually a 2D compositor) so I was looking for an easy solution to build a 3D mock up to show him. Last Saturday I download it and purchased Cheetah and by Monday I had this to show him:

yard01.jpg


I have other designs of the yard at: http://www.ricardotorres.net/yard/

Now he totally understood what I wanted to do. I want to refine the scene (I'm having so much fun with it) and that's how I came up with this transparency issue. I want to include vines on the walls and fence but I do not want to model that for obvious reasons. Texture maps with transparencies will do the trick.

Martin, my wife works for the pro-app divison of Apple (Shake, FCP pro, Motion, etc) and she showed what I had done to some of the developpers she works with. They were really impress with Cheetah :)

-Ricardo
 
Hi Ricardo,
wow you did an amazing rendering. :D Great work.

Now to your problem. Yes it is true that HDRI light doesn't pass through transparent textures. As you can see I still have to do some work in that area. That problem is already on my todo list.

I've heard about the review in the MacAddict and I'm very proud about the rating. But I haven`t seen it yet because I don't have access to the MacAddict in germany. :cry:

Thank you very much that you recommeded Cheetah3D to some Apple guys. That is really great. :D

By,
Martin
 
Ricardo : Turning on raytrace+transparency shadows did the job (I should have known that :roll: ) Indeed the artifactsproblem occurs here too. Let's hope Martin can fix it, but I'm sure he can! Need any Beta testers Martin ? :D
 
Hi Ricardo,
thank you very much for the post with the scanned MacAddict review. What a nice surprice. :D It was a great read.

Sorry but I removed the post because I was a little bit scared if it could cause copyright issues. I don't want to get in trouble with MacAddict after they have written such a great review.

Once again thank you very much.

By,
Martin
 
Article

Martin said:
Sorry but I removed the post because I was a little bit scared if it could cause copyright issues. I don't want to get in trouble with MacAddict after they have written such a great review.
Click to expand...

Oops you are right Martin. I didn't think of that. I should have just send to you the link privately. Good catch. Looking forward to future development of Cheetah. Thanks again for your hard work.

-Ricardo
 
transaprency filtering fixed in 2.3?

Martin said:
The problem is that Cheetah3D just uses anisotropic texture filtering for the primary rays. But for rays that are reflected or rays that are transmitted through a object is uses just bilinear texture filtering. So the texture behind the transparent plane won't be filtered anisotropically.

I will try to find a solution for that problem. I've put it onto my todo list.
Click to expand...

Hello Martin,

I have not had the chance to download or try the 2.3. Has this filtering problem with transparent textures been fix in this release? Thanks!

-Ricardo
 
Hi Ricardo,
sorry but I still wasn't able to solve the problem. To solve the problem I have to build in path differentials which is quite some work. But that feature has a quite high priority on my todo list. So don't worry I haven't forgotten it.

Meanwhile I will build in a switch to disable texture filtering. Not very elegant but the texture will at least look identical everywhere. You still can filter the texture with the antialiasing settings. But that is just a work around until path differntials are implemented.

By,
Martin
 
I had this problem with reflections as well: Some metallic columns that were reflecting a bump-mapped surface, showed this "noisy" unfiltered look. I enhanced it with a very __high__ antialiasing setting (32x, IIRC), but it didn't fix it 100%, it was still a bit "noisy".
 
ces said:
I had this problem with reflections as well: Some metallic columns that were reflecting a bump-mapped surface, showed this "noisy" unfiltered look. I enhanced it with a very __high__ antialiasing setting (32x, IIRC), but it didn't fix it 100%, it was still a bit "noisy".
Click to expand...

Hi,
yes that is the same problem in green. Since the filter kernel size changes when you reflect a ray at a surface. But I'm really interested to solve that problem even although it is not that easy.

v2.3.1 will solve the other problem mentioned in that thread. The problem that HDRI light doesn't pass through transparent objects. v2.3.1 will also gather HDRI light which was reflected or transmited by another surface. Check out the HDRI rendering of a metalic ring which creates nice caustics.

By,
Martin
 

Attachments

  • caustics_874.jpg
    caustics_874.jpg
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Those caustics are looking so cool Martin...

can't wait for the v2.3.1 update... :wink:

at last I have my PB back so get back to playing with Cheetah again... 1 1/2 weeks without playing with my favourite app was hell... :lol: :lol: :lol:

cheers
Trevor
 
Those caustics sure look great!!! I'm with Trevor, I can't wait!!! Does this mean that interior models will also benefit from this enhancement? Now I just don't use a glass material in my windows or add an area light. But it would be great to completely have it "naturally" lit. Keep up the good work Martin!!!

Regards,

Peter
 
Hi,
just a small note to this thread. The missing texture filtering behind transparent objects on that image will be solved in Cheetah3D 2.4.

004.jpg


v2.4 will also filter textures anisotropically which can be seen in reflections. :wink:

By,
Martin

P.S. v2.4 will also remember if a property in the properties browser was expanded. So you don't have to expand properties again and again.
 
Nice.... Thank you Martin! Good call on remembering if a property has been expanded or not. These fine brush strokes is what makes the difference between good and great software. Looking forward to it.

-Ricardo
 
Martin said:
ces said:
Check out the HDRI rendering of a metalic ring which creates nice caustics.
Click to expand...

Martin... how did you set up that ring as I have tried to do similar and can not seem to get the results that you have... or maybe post the .jas file... :lol:

cheers
Trevor
Click to expand...
 
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