Depth map and raytraced shadows

Depth map shadows :

Sử dụng map để tính bóng đổ, render nhanh, lưu và sử dụng lại được

Chất lượng của bóng đổ dựa vào qui định độ phân giải

Vật thể chỉ đổ bóng khi Cast shadow được bật. link: Render depth map shadows

raytraced shadows:

Sử dụng tia chiếu sáng để tính bóng đổ cho giống với thế giới thực, render lâu, không sử dụng lại như depth map.

Dùng để render bề mặt màu trong suốt, bóng tối mềm mại. see Render raytraced shadows.

raytraced sample:

no decay
cone angle 40
penumbra 10
dropoff: 0

raytraced shadows on:

Light radius: 2.009
shadow rays: 10
depth limit: 1

The example start with Maya's depth map and raytrace shadows. It then moves to Mental Ray's depth map and raytraced shadows.

1 Maya Renderer "Production Quality" Depth Map Shadow Resolution - 512 Filter Size - 1 Render Time - 00:03 Notes: This is the default depth map settings when launching a depth map maya render. Note that you can clearly see the pixelation of the depth map in the image.
2 Maya Renderer "Production Quality" Depth Map Shadow Resolution - 2048 Filter Size - 1 Render Time - 00:05 Notes: This is just increasing the resolution of the depth map to get clean sharp edges. Note that the increase in render time is negligible
3 Maya Renderer "Production Quality" Depth Map Shadow Resolution - 4096 Filter Size - 1 Render Time - 00:11 Notes: This high depth map resolution comes close to a raytraced looking render, but it only took 11seconds.
4 Maya Renderer "Production Quality" Depth Map Shadow Resolution - 2058 Filter Size - 6 Render Time - 00:09 Notes: The resolution has been deceased down to 2048, but the filter has been increased to soften the shadow. This is a very acceptable shadow and it only took 9 seconds.
5 Maya Renderer "Production Quality" Depth Map Shadow Resolution - 512 Filter Size - 5 Render Time - 00:03 Notes: Very fast, very soft shadow, but this begins to really show problems with depth map shadows. As the arrows indicate, a depth map shadow is soft across the whole shadow. This is not that case with true shadows or raytraced shadows. In these cases, the shadows are sharper near the casting the object and get softer as they move away.
6 Maya Renderer "Production Quality" Raytraced Shadow Light Radius - 0 Shadow Rays - 1 Render Time - 00:22 Notes: This is the default raytraced shadow. Very sharp and very accurate. The render time is twice as long as the high resolution depth map shadow above.
7 Maya Renderer "Production Quality" Raytraced Shadow Light Radius - 1 Shadow Rays - 1 Render Time - 00:36 Notes: Increasing the Light Radius softens the shadow, but it needs more shadow rays to make the soft transition. Render time is increasing rapidly
8 Maya Renderer "Production Quality" Raytraced Shadow Light Radius - 1 Shadow Rays - 10 Render Time - 02:17 Notes: The shadow rays have been increased and the shadow transitions are looking smoother. The arrows indicate that the soft shadows are more realistic as the get further from the casting object. But look at the render time!!!!! This is more than 20 times longer than the depth map. Is this really worth it - only you can answer - do you have the time? This can be the difference between a 1 day render versus a 20 day render......
9 Maya Renderer "Production Quality" Raytraced Shadow Light Radius - 2 Shadow Rays - 10 Render Time - 04:02 Notes: This just shows how far a soft shadow can go. Note the huge render time. To get these type of soft shadows, there are probably better and more efficient ways of creating them.
10 Mental Ray Renderer "Production Quality" Depth Map Shadows Resolution - 512 Samples - 1 Softness - .001 Render Time - 00:07 Notes: Same type of issues as the Maya default render.
11 Mental Ray Renderer "Production Quality" Depth Map Shadows Resolution - 4096 Samples - 1 Softness - .001 Render Time - 00:11 Notes: Good sharp fast shadow render, very similar to Maya's and at it takes about the same time.
12 Mental Ray Renderer "Production Quality" Depth Map Shadows Resolution - 2048 Samples - 1 Softness - .01 Render Time - 00:10 Notes: The "softness" parameter is very sensitive. Notice that this is currently just .01 and the shadows are already very soft. Obviously to get smooth transitions on the shadow, we need to increase the samples.
13 Mental Ray Renderer "Production Quality" Depth Map Shadows Resolution - 2048 Samples - 25 Softness - .01 Render Time - 00:10 Notes: This is very fast and beginning to be a good looking shadow.
14 Mental Ray Renderer "Production Quality" Raytraced Shadow Light Radius - 0 Shadow Rays - 1 Render Time - 00:07 Notes: This is the default raytraced shadow. Very sharp and very accurate. The render time is twice as fast as Maya's raytrace with both renderers in their default configuration.
15 Mental Ray Renderer "Production Quality" Raytraced Shadow Light Radius - 1 Shadow Rays - 1 Render Time - 00:09 Notes: Obviously samples need to be increased.
16 Mental Ray Renderer "Production Quality" Raytraced Shadow Light Radius - 1 Shadow Rays - 40 Render Time - 00:43 Notes: This is a very good render. Note the shadow of the nail. And it took only 43 seconds, compared to Maya's 2:17
17 Mental Ray Renderer "Production Quality" Raytraced Shadow Light Radius - 2 Shadow Rays - 40 Render Time - 00:45 Notes: Another magnitude of softness does not dramatically increase the rendering time.