saved IR maps/light cache

[ckat609]

Hey guys, I have a couple of questions...

 

If I make a 320x240 IR map and load it to render a 1024x768 image... will it have the same quality as if I rendered single pass on the same 1024x768 image?

 

After an IRmap is saved and then loaded... what will we be able to change without having to generate another map? I mean... object positions, dimensions, parameters in materials, in cameras, in the renderer rollouts, etc...

 

Same question for light cache...

 

Thanks!

[Ricardo Eloy]

General answers:

- no, it won't have the same quality. I believe the calculations are resolution-dependent, so if you want high quality, you gotta do it high res

- You can change some parameters, but camera and object positions are part of the calcs. Once you change them, the calcs won't work the way you would like them to.

[Brian Smith]

In animations where only the camera moves, the irradiance and light cache maps don’t change over time. If you move any light or renderable object or animate any textures, the maps change from one frame to another because light will be bouncing around differently from one frame to another. That's not to say you can never change these things without recalculating, you just can't do it much at all or to objects in your foreground - otherwise the effects will be noticeable.

 

Irradiance and light cache maps are view dependent, meaning that samples are calculated at each frame for only those areas of a scene in view during a particular frame. For this reason, new samples must be calculated for every different view but only in those areas of the scene that weren’t previously in view. Samples taken in previous frames can be saved and used in future frames to reduce the amount of samples, and therefore time, to calculate the future frames.

[ckat609]

Gotcha, thanks a lot!!! I was asking this because I've never done an animation using vray as my renderer... so with both IR maps and light cache... For an animation what should i use? single pass, incremental, etc????

 

Thanks again guys!

[Ricardo Eloy]

Incremental. The thing is: when you move only tha camera, you can save your calcs for each frame and then render the animation using only one map. As Brian said, if you don't recalculate, when you move your camera you'll get dark areas where you couldn't see before.

[ckat609]

Thanks!!! What about Light cache? Should I use fly-through? I'm trying to render an interior... just moving the camera... no other objects will be moving.

 

I was reading a tutorial somewhere where it said light cache doesn't handle bump maps as well as the rest. What exactly does this mean? I have brick walls here and there and some "stucco" texturing on others... should I be concerned? Does this mean I'll have to increase my bump amount or it won't work at all?!?

 

Would it be better if I used IR for my second bounces? Will it render faster? Will it look better?

 

Sorry for all these questions... they just came to me when I read that tutorial.

 

Thanks again!!!

[Brian Smith]

Yes. Set to Fly-through...straight from a tutorial in the online manual:

 

1.13. Render frames 0 and 360 for reference.

 

The light cache doesn't look bad, but we will need to calculate it for the entire walk-through animation, and not for a single frame only. Note that this is not strictly necessary - we can render the animation with the light cache being calculated each frame; however, rendering it only once will save rendering time, especially for long animations.

 

1.14. Set the light cache Mode to Fly-through. Make sure that the timeline animation range matches the range which you want to render. This is important because the light cache will look at the current timeline animation range when calculating the fly-through cache.

 

Since all the light cache samples will be distributed among all the animation frames, we will need to increase the light cache Subdivs value. The exact value depends on the quality you want to achieve and on your specific animation. If the camera moves slowly, or the path is relatively short (e.g. just one room of a house) then you can use lower Subdivs value, since most of the samples will fall in the same place anyways. If the camera moves quickly or covers larger parts of the scene, you will need more samples to get adequate coverage everywhere.

 

1.15. Set the light cache Subdivs to 2000.

 

1.16. Render frame 360 for example. Note that although we render only one frame, the Fly-through mode forces the light cache to be computed for the entire animation:

 

During the fly-through mode, the preview display of the light cache is not very useful, since it shows samples from the entire camera path. The following image shows the preview display while the light cache is being calculated:

 

Now that we have computed the light cache, we need to see if it is good enough for our needs. We can do this by rendering several different frames with the same light cache.

 

1.17. Save the light cache to disk, for example to lightcache.vrlmap.

 

1.18. Set the light cache Mode to From file and select the saved file name.

[ckat609]

Thanks! I didn't quite get it though So I should only render the first and last frames of the animation? Do you have the link to that tutorial so I can read the whole thing?! Sorry for being such a pain.