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Problem: Too much grain in the image.

ComanderComander Posts: 52
in Technical Help (nuts n bolts)

Hello everybody.

I would like an image in Iray - create quality and indeed in a parking garage. As a light source, I use a light shader from DAZ product called Real Lights. Everything looks great in preview render but in later render the image looks very grainy. Added to this is the the render bar is 1%, and after 2 hours simply ceases to render. The image looks as if it is not finished gerendet. I was recommended the exposure value in the Tone Mapping Settings to settle down instead of 13 to 5. I heard 5 would be good for the inside and 13 outside for pictures. On the ceiling of about 30 with 60 watts with Fluorescent hanging lamps. The preview showed overexposure. After that I did the lumen to the value. 5 turned down where the preview looked perfect. However, when rendering the rough spots (grain) rendering were still present. Also went only to 1%.

Question: What can I do that the picture loses the Grain?
            Do I support the area with spotlights or Point Lights or may
            the room filled enough with shaders.

Thank you for your reply

Comments

  • Richard HaseltineRichard Haseltine Posts: 100,961

    Try lowering the exposure value even more. Also, even a 60 light is not going to do much in a big space unless it is one of many - think of how dime a 60 watt buld is in even in a small room.

    Your render stops after two hours because, under Progressive, there are three stop-conditions - time, convergence and samples - and the render stops when it hits any one of them. Increasing Max Time (it's in seconds) will give a longer render, or set it to 0 to exclude time as a stop-condition.

  • ToborTobor Posts: 2,300

    The slow, "grainy" renders are often the result of insufficient light. The tone Mapping settings have no effect on adding light for the Iray engine. They only manipulate the appearance of the output canvas.

    Changing both the lights and exposure control will just confuse your results. Go back to a normal tone mapping for an indoor scene -- go from f/8 to maybe f/5.6 or f/4, then adjust the position and brightness of your lights. If by "preview" mode you mean you have activated the nVidia Iray mode in the viewport, this only approximates the finished output. But if by preview you mean the basic Texture Shaded view, this is by no means accurate.

    Render to a small window to start -- 300px is all you really need to judge light levels. As you approach a good lighting balance and render speed, THEN play with the Tone Mapping to fine-tune. When everything is set, render to a full size window.

  • tring01tring01 Posts: 305

    I had this issue as well today.  No matter what I tried I couldn't get anything but a heavily grainy render.  I pulled the plug.  Deleted the scene and reset my render settings to default.  Created the scene again and it rendered fine.  I'm not saying this is always the solution, bit I've noticed Iray in Daz generally doesn't like it if you make a lot of changes to a scene (changing skins, shaders, skins, repeatedly).  Something can go wonky.  Anyway, hope that helps.

  • ComanderComander Posts: 52
    Tobor said:

    The slow, "grainy" renders are often the result of insufficient light. The tone Mapping settings have no effect on adding light for the Iray engine. They only manipulate the appearance of the output canvas.

    Changing both the lights and exposure control will just confuse your results. Go back to a normal tone mapping for an indoor scene -- go from f/8 to maybe f/5.6 or f/4, then adjust the position and brightness of your lights. If by "preview" mode you mean you have activated the nVidia Iray mode in the viewport, this only approximates the finished output. But if by preview you mean the basic Texture Shaded view, this is by no means accurate.

    Render to a small window to start -- 300px is all you really need to judge light levels. As you approach a good lighting balance and render speed, THEN play with the Tone Mapping to fine-tune. When everything is set, render to a full size window.

                          Thanks for the help. It has worked very well.

  • ComanderComander Posts: 52
    tring01 said:

    I had this issue as well today.  No matter what I tried I couldn't get anything but a heavily grainy render.  I pulled the plug.  Deleted the scene and reset my render settings to default.  Created the scene again and it rendered fine.  I'm not saying this is always the solution, bit I've noticed Iray in Daz generally doesn't like it if you make a lot of changes to a scene (changing skins, shaders, skins, repeatedly).  Something can go wonky.  Anyway, hope that helps.

                                                                                                              Thanks for the tip. Nice to see that I did not own the problem.

     

     

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