Jump to content

Sign in to follow this  
Maarten Vis

Render artefacts on edges

Recommended Posts

Hello friends,

 

I'm doing a render of my house and it's getting close to where I want it to be. But I keep running into artifacts on the edges. (see picture)

 

I use the physical renderer with global illumination, primary QMC and secondary Light Mapping. I use a camera with a f11 and 4 sec exposure.

 

Thanks in advance for the help!

 

Cheers,

 

Maarten

LBG_282_15c.jpg

Share this post


Link to post
Share on other sites

I think in many cases it´s caused by low samples value. Try to increase samples and with render region command try on critical place...

Share this post


Link to post
Share on other sites

This can also be GI-Bleed. Do the walls have volume or are they flat sheets? This tends to happen when walls are thinner than the samplesize, as the sample gets averaged with samples outside (which are very bright) and samples inside (which are very dark). When using any non-QMC-GI you should always work with volumes. It's not an issue with QMC as it works on a per pixel basis but it's best practice to always model with volume anyways.

Share this post


Link to post
Share on other sites
1 hour ago, DasFrodo said:

This can also be GI-Bleed. Do the walls have volume or are they flat sheets? This tends to happen when walls are thinner than the samplesize, as the sample gets averaged with samples outside (which are very bright) and samples inside (which are very dark). When using any non-QMC-GI you should always work with volumes. It's not an issue with QMC as it works on a per pixel basis but it's best practice to always model with volume anyways.

 

Very much appreciated to have a good technical explanation for why this happens. I learned something today ! 🙂 Thanks DF.

 

CBR

Share this post


Link to post
Share on other sites
7 minutes ago, Cerbera said:

 

Very much appreciated to have a good technical explanation for why this happens. I learned something today ! 🙂 Thanks DF.

 

CBR

 

Glad I could teach you something for a change 😆

Share this post


Link to post
Share on other sites
  • Topic Author
  • On 11/22/2019 at 3:31 PM, DasFrodo said:

    This can also be GI-Bleed. Do the walls have volume or are they flat sheets? This tends to happen when walls are thinner than the samplesize, as the sample gets averaged with samples outside (which are very bright) and samples inside (which are very dark). When using any non-QMC-GI you should always work with volumes. It's not an issue with QMC as it works on a per pixel basis but it's best practice to always model with volume anyways.

     

    Thanks for the help so far! I have extruded the walls and ceiling from splines. Could that be the issue? Would it be better to rebuild them using objects with volume?

     

    And I don;t get why you say 'when using any non QMC-GI' because I am using QMC? Or am I missing something.

     

    Cheers, Maarten

     

    Share this post


    Link to post
    Share on other sites
    3 hours ago, Maarten Vis said:

    I have extruded the walls and ceiling from splines. Could that be the issue?

     

    That may well be the issue if there any gap at all between these forms. Ideally they should all be one surface.

    Although the issue with light leakage with flat planes applies to IC / LM only, it applies to everything if there are any gaps at all in your surfaces....

     

    CBR

    Share this post


    Link to post
    Share on other sites
    On 11/23/2019 at 7:55 PM, Maarten Vis said:

     

    Thanks for the help so far! I have extruded the walls and ceiling from splines. Could that be the issue? Would it be better to rebuild them using objects with volume?

     

    And I don;t get why you say 'when using any non QMC-GI' because I am using QMC? Or am I missing something.

     

    Cheers, Maarten

     

     

    You said you are using QMC for primary and LM for secondary, so your setup is not all QMC 😉 that's where the leaks are coming from, I think.

    Share this post


    Link to post
    Share on other sites
  • Topic Author
  • 11 hours ago, DasFrodo said:

     

    You said you are using QMC for primary and LM for secondary, so your setup is not all QMC 😉 that's where the leaks are coming from, I think.

    You're absolutely right! When I switch to Irradiance cache for the second method the problem dissappears. Downside is that the rendering becomes extremely long. (14 hours and counting for a 800 x 530 image!) I'd love to know how to get those render times down!

     

    Share this post


    Link to post
    Share on other sites
    44 minutes ago, Maarten Vis said:

    You're absolutely right! When I switch to Irradiance cache for the second method the problem dissappears. Downside is that the rendering becomes extremely long. (14 hours and counting for a 800 x 530 image!) I'd love to know how to get those render times down!

     

    That's odd. Light leaks can happen with IC as secondary as well, as it's an interpolated technique as well. If you want to really have accurate lighting you need to go QMC + QMC or fix your walls, if you didn't do that already.


    QMC + QMC is very slow but by far the best result as it's completely per pixel and no interpolation whatsoever. You can even disable Ambient Occlusion with this as the detail in the shadows comes from the QMC itself 🙂

    Share this post


    Link to post
    Share on other sites
  • Topic Author
  • 4 hours ago, DasFrodo said:

    That's odd. Light leaks can happen with IC as secondary as well, as it's an interpolated technique as well. If you want to really have accurate lighting you need to go QMC + QMC or fix your walls, if you didn't do that already.


    QMC + QMC is very slow but by far the best result as it's completely per pixel and no interpolation whatsoever. You can even disable Ambient Occlusion with this as the detail in the shadows comes from the QMC itself 🙂

    Thanks, I am doing that as we speak. It's actually faster than the QMC + IC option! But indeed still quite slow 🙂

    Now that we're on the subject, do you know any good recourses for learning about best practices for render speed? ( am completely self taught in C4d, so 'm probably  making tons of mistakes 🙂

    Share this post


    Link to post
    Share on other sites
    1 hour ago, Maarten Vis said:

    Thanks, I am doing that as we speak. It's actually faster than the QMC + IC option! But indeed still quite slow 🙂

    Now that we're on the subject, do you know any good recourses for learning about best practices for render speed? ( am completely self taught in C4d, so 'm probably  making tons of mistakes 🙂

    To be perfectly honest I'm completely self-taught as well. All I ever did was look at the C4D documentation (which tells you A LOT about renderspeed when it comes to GI at least) and tried stuff out. Surely there's tons of good tutorials out there, but I don't know which are. Maybe @Cerbera or @Igor ?

    Share this post


    Link to post
    Share on other sites

    Join the conversation

    You can post now and register later. If you have an account, sign in now to post with your account.

    Guest
    Reply to this topic...

    ×   Pasted as rich text.   Paste as plain text instead

      Only 75 emoji are allowed.

    ×   Your link has been automatically embedded.   Display as a link instead

    ×   Your previous content has been restored.   Clear editor

    ×   You cannot paste images directly. Upload or insert images from URL.

    Sign in to follow this  

    • Recently Browsing   0 members

      No registered users viewing this page.

    ×
    ×
    • Create New...