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    Problems with realistic lighting

    Hello everyone.
    I'm trying to recreate a scene from 3ds Max Design 2011 into UDK.
    For my project, photorealistic lighting plays an important role.

    I have a relatively simple scene with a room and a yard just outside a door.
    The room is lit with a point light and there is also sun light outside (i made it with dominant directional light + sky light).

    The problem is that I want the light from the "sun" to come into the room through the door windows. From what i have done so far, this is what i get:



    That light entering is definitely not the one I was expecting to see coming through the door's windows.
    In case it is needed, here are the properties of the lights:

    DominantDirectionalLight properties:


    SkyLight properties:


    PointLight properties (the light in the center of the room):



    Also, the properties and the uv's of the door mesh:


    I have not included the properties for the windows, because they are BSPs with a translucent material + a RTT for reflections.

    Any help will be greatly appreciated!

    #2
    Originally posted by JChrist View Post
    For my project, photorealistic lighting plays an important role.
    UDK is not raytracing engine, it is game engine. All lighting effects are fake, not raytraced. UDK will not calculate all those things and apply them automatically. You need to make all that by hand.

    "the devil's in the details". Some ideas i though about:
    Ambient occlusion: http://www.chrisalbeluhn.com/UDK_Amb..._Tutorial.html
    Special materials, that can fake some effects. Like reflections, shiny diffused light. All those little things help convince brain its all real.
    A bit of postprocess with distance blurr can make scene look softer.
    Some animated (or just speed tree) tree with dynamic shadow could be nice in scene.
    Transparent material in windows with bit of distortion, and modulating color or intensity.
    few transparent meshes with golden, shiny particles noise to fake dust particles inside light volumes from windows and door.


    You can also look into udk tech demo and see how epic artists made all those little tricks for your brain to believe that udk is realtime raytracing application.

    Also look there, somebody with almost your problem, but for UT3 and udk later:
    http://forums.epicgames.com/showthre...ht=great+scene
    http://forums.epicgames.com/showthread.php?t=707296
    Maybe you can contact him for better advice.

    Comment


      #3
      The major problem (imo) is that you're using a skylight.
      Lightmass should be enough for taking care of the ambient lighting...
      if you 're not familiar with its use take a look at the documentation pages.

      Comment


        #4
        Thank you for your responses.
        UDK is not raytracing engine, it is game engine. All lighting effects are fake, not raytraced. UDK will not calculate all those things and apply them automatically. You need to make all that by hand.
        Now, I know that real-time photorealism will not happen and I need to make tweaks to get a result that seems to be realistic, but I just can't figure out how to make that lighting effect I'm explaining (the sun light coming in from the door windows).
        Thanks for the links, I checked them out and I will try to see where these can get me.

        The major problem (imo) is that you're using a skylight.
        Lightmass should be enough for taking care of the ambient lighting...
        As for the SkyLight, I started without it at first, but I can't produce the lighting effects, either with it, or without it.

        Comment


          #5
          1. Increase lightmap resolution on all those surfaces (note that BSP surfaces are measured in unreal units per pixel, ie lower is sharper. Opposite on everything else)

          2. Get rid of the skylight and use environmental lighting instead. You can find it in your world properties. Use really low intensity and let the bounce lighting do most of the work.

          3. Turn on ambient occlusion computing in the world lightmass properties also, play around with the radius and other occlusion settings.

          Some pics regarding the skylight:

          Skylight:
          [shot]http://i211.photobucket.com/albums/bb309/Xendance/skylight.jpg[/shot]

          Environmental:
          [shot]http://i211.photobucket.com/albums/bb309/Xendance/noskylight.jpg[/shot]

          Also, here is skylight with shadows on:
          [shot]http://i211.photobucket.com/albums/bb309/Xendance/skylightshadowson.jpg[/shot]

          Comment


            #6
            Now, I know that real-time photorealism will not happen and I need to make tweaks to get a result that seems to be realistic, but I just can't figure out how to make that lighting effect I'm explaining (the sun light coming in from the door windows).
            The light shafts in UDK is only visible while looking directly at a prominent light source IE, the sun. The effect you're looking for is simply a faked light using static meshes.

            Comment


              #7
              I think i did not explain well what is going on with udk. It has very basic raytracing, most effects you need to fake manually. No light tweaking will add reflection or shine to simple material.

              List or even render from MAX with description what you want would make easier to explain what is possible, what can be done with light tweaking and what needs some extra work or tricks.

              Also be ready for making complicated materials, you need those for realistic feel of scene.

              Comment


                #8
                I'm thinking the problem is the shape of the cast shadow here?
                4 small windows in the door laid out in a rectangle pattern, but the shadow on the floor looks almost like a cross?

                Or, is something else your main concern? Over brightening or something?

                Comment


                  #9
                  raise the resolution of the lightmap on your objects. Its currently at 32, which by default is very low. For something thats receiving and casting shadows from your direct light, I'd start with 256.

                  Comment


                    #10
                    Originally posted by percydaman View Post
                    raise the resolution of the lightmap on your objects. Its currently at 32, which by default is very low. For something thats receiving and casting shadows from your direct light, I'd start with 256.
                    Also note that if you are using any bsp brushes, the light mapping goes in reverse down to 1. Best to set the bsp faces that are receiving light to around 4 or 8. Ones not being lit set them as high as you want.

                    Comment


                      #11
                      Originally posted by Wyldhunt View Post
                      I'm thinking the problem is the shape of the cast shadow here?
                      4 small windows in the door laid out in a rectangle pattern, but the shadow on the floor looks almost like a cross?
                      Set Cascaded Shadow maps Radious (dom. dir. Light properties) to something like 1024 in order to fix that.
                      In any case from what I can see in your scene I believe you need to study and test udk's lighting system a bit more before attempting to light up your map.

                      Comment


                        #12
                        Thank you all for your responses.

                        My problem was exactly what Wyldhunt mentioned, the fact that the sun light entering from the door windows wasn't making a cross-like shadow.
                        I managed to fix this by lowering the lightmap resolution of the BSPs, thanks KenD for mentioning it!

                        Here is my new (improved) screen shot:


                        Now, I am going to check out the environmental lighting.
                        Thanks again!

                        Comment

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