Master Zap to the rescue!

loocas | 3ds Max,technical | Wednesday, June 3rd, 2009

I knew I’d not only get an answer but a complete solution to my black lines problem with mental ray, when I ask no other than the big Mr. Zap himself!

He pointed me to a discussion of this issue in mental ray, which turned out to be a NaN issue in floating point value pixels. Thankfully, there also was a solution to this problem, which was to use, one of mr’s great features and advantages (custom shaders), a Lens shader written by David Landier.

This, D3DBlackSpotsRemover lens shader does a simple math to check for a value of each pixel and fixes it if it finds a deviation.


Thankfully, this bug has been fixed in 3ds Max 2010, but I’m yet to test it out to see for myself and seems to be working just fine, which is awesome news! Anyways, big, big thank you to Master Zap and David Landier of course, they’re the men when it comes to mental ray!

Edit: Sorry for not posting the direct link to the shader, here it is over at David’s site.
The site is a bit confusing, so I took the liberty and mirrored the shader on my server, without permission however, so if you read this, David, and don’t want me to mirror your shader, let me know and I’ll take it down immediately.
Here’s the mirror: DL3D_BlackSpotsRemover


  1. Well dangit! You are such a teaser! You go and tell us about this wonderful lens shader, but don’t tell us where to get it :p

    I tried going to David Landier’s site via the link you provided above, and it’s a total mess. The website seems to be experiencing some sort massive breakdown and is currently about 90% error messages.

    Comment by Takuan — June 3, 2009 @ 13:50

  2. Ah, sorry mate, I didn’t realize the site is such a mess.
    Yes, it’s available under the Downloads > Download Shaders menu. But I’ve added the direct links to this article. ;)

    Comment by loocas — June 3, 2009 @ 16:07

  3. Looks like he’s got his site sorted out now, as well :-)

    Thanks for the info, I’m pretty excited to check this out!

    Comment by Takuan — June 4, 2009 @ 03:02

  4. Hi there – im having this problem with the black lines on my renders and so inserted the shader but nothing has changed. I have checked and double checked to make sure ive not made a mistake but cant get rid of the black lines. Any thoughts? Thank you

    Comment by Alex — April 7, 2010 @ 22:50

  5. Hi, Takuan,

    I’d love to help you out, but if this didn’t help you, unfortunately, I don’t know what could. I’m not a mental ray guru, like Master Zap, so, try contacting him, or read through his blog.

    All the best.

    Comment by loocas — April 8, 2010 @ 08:40

  6. Thanks for the tip! It solved my problem. I have a question tho, is there a way to use multiple lens shaders in 3ds max 2009? Sry if this is a noob question.

    Comment by Jeremy — February 22, 2011 @ 23:40

  7. Heya, Jeremy,

    glad to have helped. As for the question, well, to be perfectly honest, I have no idea as I don’t use mental ray that often (well, almost at all). :(

    Comment by loocas — February 23, 2011 @ 00:01

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