Things that slow down a render

I was working on a quick scene (rotfl....hahahaha...wait for me to catch my breath...ok, I'm ready).  It has a door prop, some grass, trees, rocks, ivy and no visible sky.  I needed a test render and for some unknown reason I had it on premium with true ambience and TA correction and reflection correction at 16 max and 6 depth instead of regular rendering.  After a bit I realized that it was going to take a while but it was already 13% so I thought I'd let go.  This was about 3pm.  I let it run through the night and checked it at 9am and it was at 89%.  Now I'm unhappy.  I don't even know if the picture looks good.  I just wanted a test render.

What could be causing this to take so long?   Horo, you've shared some of things like the render settings but what in my scene is causing it to be so slow?

 

Comments

  • ChoholeChohole Posts: 33,604

    The two most common things to waste time in renders are transparency and reflection.  Quite probably your trees have trans on the leaves  and you do mention reflection.

  • NGartplayNGartplay Posts: 1,829

    Thanks Chohole, first thing that I do is remove the reflection correction...or was it blurry reflections?  I don't remember anymore.

    Do trees that are behind the camera slow down the render time?  I have them to create tree shadows in my scene.

  • HoroHoro Posts: 8,201

    Chohole is right (of course, as always). Additionally, TA (True Ambience) takes a lot of time, also because you have to use a high rays per pixel (rpp) setting. Enabling Boost Light together with TA helps to reduce the noise. If you use TA for landscape renders with IBL, check with and without True ambience optimization (arrow right of HDRI Effect). Plop rendering critical parts is your friend to optimise render speed (or rather reduce render hogging). If you use a volume slab for clouds make sure to Exclude it from IBL rendering because it slows the render considerably down but there's no difference in the end result.

  • NGartplayNGartplay Posts: 1,829

    Thank you Horo for the information.  I should have stopped this render way before I went to bed as it wasn't my final render but now it's so far along I'm going to let it finish.  I have to be careful not to do this again.

    I did ask about trees behind the camera.  Does anyone know if they take up render time?

  • HoroHoro Posts: 8,201

    Not too much but if the sun is behind them, they may cast shadows into the visible scene and thus need some time.

  • NGartplayNGartplay Posts: 1,829

    Thank you so much Horo and Chohole!

  • ed3Ded3D Posts: 1,206
    edited December 2020

    ~  and    "Could'nt"    you use Default render settings for Test  and then  "Turn-it Up "  for Finals  ??  thanx  ~

    **  and also the Spot Render  for Test on " Finals "   ~

    Post edited by ed3D on
  • ed3Ded3D Posts: 1,206
    edited December 2020

    NGartplay said:

    Thank you Horo for the information.  I should have stopped this render way before I went to bed as it wasn't my final render but now it's so far along I'm going to let it finish.  I have to be careful not to do this again.

    I did ask about trees behind the camera.  Does anyone know if they take up render time?

    +  and also Any items    "behind the camera "     Select  and then 'Hidden'  _

    Post edited by ed3D on
  • NGartplayNGartplay Posts: 1,829

    Yes, thank you!

  • ed3Ded3D Posts: 1,206

    ~   and You're welcome  _

  • SlepalexSlepalex Posts: 905

    ed3D said:

    NGartplay said:

    Thank you Horo for the information.  I should have stopped this render way before I went to bed as it wasn't my final render but now it's so far along I'm going to let it finish.  I have to be careful not to do this again.

    I did ask about trees behind the camera.  Does anyone know if they take up render time?

    +  and also Any items    "behind the camera "     Select  and then 'Hidden'  _

    Maybe "select" and "delete"?
    To reduce the file size. After all, these objects for rendering do not exist? 

  • HansmarHansmar Posts: 2,221

    If you want to have shadows from objects behind the camera, you cannot hide or delete them. What you could do to lower render time (I think) is to replace 3D trees with 2D versions. Not sure whether that helps a lot, but it is worth a shot. From the shadows you should not be able to tell what made them.

  • NGartplayNGartplay Posts: 1,829

    That's a great idea Hansmar.  I do have some 2D trees from FoleyPro.  The transparent part is not completely transparent though.  I have used them for distant trees.

    thanks Slepalex

  • SlepalexSlepalex Posts: 905
    edited December 2020

    Hansmar said:

    If you want to have shadows from objects behind the camera, you cannot hide or delete them. What you could do to lower render time (I think) is to replace 3D trees with 2D versions. Not sure whether that helps a lot, but it is worth a shot. From the shadows you should not be able to tell what made them.

    2D trees with an alpha channel instead of the 3D to reduce rendering time?
    A very bad idea! This will increase the render time.
    If the shadow from the Bryce tree will increase the render time, it will be 0.0001%.

    Post edited by Slepalex on
  • SlepalexSlepalex Posts: 905

    NGartplay said:

    That's a great idea Hansmar.  I do have some 2D trees from FoleyPro.  The transparent part is not completely transparent though.  I have used them for distant trees.

    thanks Slepalex

    If the image for a 2D tree is very large, then this will not only increase the render time, but also increase the file size.
    If you want to get the foreground shadow from the trees behind the camera, make the largest foliage and fewest leaves in a regular Bryce tree. This tree will "weigh" a little, but will give a thick shadow.
    But all this is not very good advice. The best advice: behind the camera, use clones (Strl + I, Alt + I) of the trees that you have in the scene. This will not increase the render time (unless by a few seconds). In general, you are not looking there. It is not the number of objects in Bryce that greatly affects the render time, but their properties. 

  • SlepalexSlepalex Posts: 905

    NGartplay said:

     I do have some 2D trees from FoleyPro.  The transparent part is not completely transparent though.

    Show me a material of 2D tree here and I'll tell you what to do. 

  • NGartplayNGartplay Posts: 1,829

    Hi Slepalex, thank you for the information on the shadows.  I have tried instancing using the file commands with little success but I will try the keyboard command ALT-I

    Hi have to open Bryce and look for my 2D trees again.  I'll do that now.

  • SlepalexSlepalex Posts: 905

    NGartplay. In general, Chohole briefly explained everything to you. The alpha channel increases the render time by several times. Without seeing your scene, materials, render settings, etc., it is very difficult to judge what is the reason for the long rendering. You mentioned ivy. This is most likely an object from the IvyGenerator program. This is 100% alpha channel. There is a lot of alpha channel. In recent years, I do not use imported trees with alpha channel in foliage at all. I'd rather use trees from Arbaro weighing 300,000 polygons, but with geometric foliage without an alpha channel, than trees from xFrog weighing 10,000 polygons, but with an alpha channel in the foliage.
    Of course, if you want to apply high-quality textured foliage in the foreground, but with an alpha channel, then get ready for a long render. At one time, back on Bryce 5, I had a week-long render on a simple still life (cherries and a glass of wine), a Pentium 4 processor. Brycer C-Ram for a good high-resolution landscape (with TA 36 - 64 rpp) had a render duration of a month or more for modern computer. Art requires sacrifice!

  • NGartplayNGartplay Posts: 1,829
    edited December 2020

    Slepalex, I tested some 2D trees and they were fine.  I then remembered that I had shadows while doing a space scene and I was trying to use 2D planets, star fields and propulsion and they all had shadows from the transparent part.  Or I could see in the scene the transparent part.  I just loaded them into the default Bryce scene and none of them created an issue.  The space scene with the problem used a HDRI in the atmosphere.

    JScott 2D pine in front and FoleyPro distant trees.

    Art requires sacrifice, lol.  Yes it does.  A week long render would ruin my week.  And I just bought the XFrog tree package.

    transparent-trees.jpg
    800 x 800 - 336K
    Post edited by NGartplay on
  • SlepalexSlepalex Posts: 905

    NGartplay said:

    Slepalex, I tested some 2D trees and they were fine.  I then remembered that I had shadows while doing a space scene and I was trying to use 2D planets, star fields and propulsion and they all had shadows from the transparent part.  Or I could see in the scene the transparent part.  I just loaded them into the default Bryce scene and none of them created an issue.  The space scene with the problem used a HDRI in the atmosphere.

    JScott 2D pine in front and FoleyPro distant trees.

    Art requires sacrifice, lol.  Yes it does.  A week long render would ruin my week.  And I just bought the XFrog tree package.

    Here you can see that 2D trees are flat. They lose their expressiveness, since they do not have their own inner shadows. It looks like a children's coloring book. If you have a modern computer, then don't be afraid to use cloning and Instancing Lab. And good lighting with a Render Premium, Soft Shadows, True Ambience (no less than 36 rpp). Maximum Ray Depth 4 is possible. 

  • SlepalexSlepalex Posts: 905

    NGartplay, here's the landscape. Scene file description:
    Bryce 7 Pro. Premium TA 36 rpp render with soft shadows. Render time 2:35:14.
    Lighting: Bryce Sky HDRI, Distant Light.
    Modeling in Bryce, Wings 3D, Arbaro.
    File size 19.9 MB.
    In addition, on the birch on the right and on the cloned Bryce tree by default (by the way, I used the default tree for the first time), the foliage has a translucency according to the Rashad Carter method. The tree on the left in the background does not have transparent foliage, but only has an increased Ambience value (5 - 10). If not for the transparent foliage, the render time would have been no more than an hour. This is despite the fact that the TA 36 rpp render with soft 100% shadows from Distant Light. The sun is turned off here and is located to the right of the scene to give the cumulus clouds the desired shade. Even if the sun is off, its azimuth and altitude affect the color and hue of the clouds.

  • SlepalexSlepalex Posts: 905

    Here's another landscape.
    Bryce 7 Pro. Premium TA 36 rpp render with soft shadows. Render time 1:40:40.
    Lighting: Sun, Bryce Sky HDRI, Spotlight, Radial Light.
    Modeling in Bryce, Wings 3D (church), Arbaro, freebies from the net (two tall houses).
    File size 26.6 MB.
    Water has no transparency. What for? Specularity and Reflection only. Some trees have translucent foliage. If not for this, the render time would be no more than 40 minutes.

  • SlepalexSlepalex Posts: 905

    Here's another landscape.
    Bryce 7 Pro. Render Premium TA 36 rpp. The render time is 1:51:11.
    Lighting: Sun, Spotlight, Bryce Sky HDRI.
    Modeling in Bryce, Wings 3D, Arbaro.
    The file size is 10 Mb.
    Here foliage and grass have some transparency. However, render times are short.

  • NGartplayNGartplay Posts: 1,829
    edited December 2020

    Those are two gorgeous landscapes.  The default tree in the first image looks excellent.  The sky in the second is so pretty.

    I really appreciate the explanation of the transparency.  It will help when I am creating my scenes so that I can make decisions on construction with render times in mind.

    Post edited by NGartplay on
  • mermaid010mermaid010 Posts: 3,576

    Wow Slepalex, absolutely beautiful renders, I love them

  • adbcadbc Posts: 1,898

    Slepalex : awesome renders.

  • HoroHoro Posts: 8,201
    edited December 2020

    Slepalex - very nice examples. I had bought a lot of Xfrog trees a long time ago and almost never use them because the leaves are made of 2D faces with pictures and render slow. I either use Bryce trees or Arbaro trees, those leaves are meshes and can be set to produce translucency. This takes also time to render but the difference of the outcome is dramatic. Yes, Bryce and Arbaro trees take more memory but they can be instanced and thus use much less memory.

     

    Post edited by Horo on
  • HansmarHansmar Posts: 2,221
    edited January 1

    Slepalex said:

    Hansmar said:

    If you want to have shadows from objects behind the camera, you cannot hide or delete them. What you could do to lower render time (I think) is to replace 3D trees with 2D versions. Not sure whether that helps a lot, but it is worth a shot. From the shadows you should not be able to tell what made them.

    2D trees with an alpha channel instead of the 3D to reduce rendering time?
    A very bad idea! This will increase the render time.
    If the shadow from the Bryce tree will increase the render time, it will be 0.0001%.

    Thanks Slepalex, for correcting my error. And as you indicate, instancing is, of course, the way to go. And your landscapes are wonderful.

    Post edited by Hansmar on
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