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HolyMonkey-
12-11-2011, 02:19 AM
I have a radiosity "problem". When it comes to time it takes to render out a animation to images.

I keep my files on a external harddrive, and I open them up from there and use it from there, can that have anything to do with the slow render? That it doesn't use the full potential of my PC?

The reason I say this is because, whenever I open a scene and do a testrender for a single frame. The rendertime is usually 3-6 minutes, that includes calculating radiosity.

Then I bake out and cache the radiosity, and an animation of 1200 frames tend to shoot upto a render time of over 130 hours.

What I notice is that it always have to recalculates the radiosity samples at every frame before it starts rendering the polygons(green bar). However, the green bar takes alot more time rendering out 1 frame when its rendering a scene, than it takes when it just renders out a single frame.

Average time per frame without radiosity bake(cache) - 3-6 minutes.

Average time per frame with radiosity bake rendering out the entire scene - 10-12 minutes.

Why does the time explode when I render out scenes?

My render settings are by the way MonteCarlo I also checked out this thread, http://forums.newtek.com/showthread.php?t=124228 Similar problem but not quite.

I tried uploading my scene here with a link but there are limited downloads, let me know and I'll send you the scene.

JonW
12-11-2011, 05:36 AM
You can keep the files anywhere it's not going to slow things down, maybe a second but no more than that depending on your network.

After you have baked the Radiosity make sure you change the Preprocess from Automatic to Locked. Also sometimes LW has problems finding the Radiosity file & is redoing every frame because it can't find it.

If you have spent many many hours baking it &/or adding to it with other cameras, make a spare copy first just in case you wipe it accidentally. Then check your paths to it. You can rename it to make things easier to track down just make sure that the file & everything matches.

If nothing is changing or moving in the scene & only the camera is moving, do not tick Animation.

HolyMonkey-
12-11-2011, 08:42 AM
You can keep the files anywhere it's not going to slow things down, maybe a second but no more than that depending on your network.

After you have baked the Radiosity make sure you change the Preprocess from Automatic to Locked. Also sometimes LW has problems finding the Radiosity file & is redoing every frame because it can't find it.

If you have spent many many hours baking it &/or adding to it with other cameras, make a spare copy first just in case you wipe it accidentally. Then check your paths to it. You can rename it to make things easier to track down just make sure that the file & everything matches.

If nothing is changing or moving in the scene & only the camera is moving, do not tick Animation.

I actually ticked locked, and the render time went down to 13 hours yaay, although I tweaked the settings down quite a bit aswell,

What does locked really do?


What I did
I turned off AO, Directional Rays, and Volumetric Light in the Gi menu. Lowered the settings from 500 rays to 250, and like 2 secon 8 and

I ticked in locked.

140 to 13 hours

Thanks about the radioisity cache file path thing. Wont save that file on the server anymore.

JonW
12-11-2011, 01:34 PM
Locked means that LW has to use the radiosity that has been baked & not change it.

Is your object nice & tidy, joins welded, no non planar polys? LWCad has a great tool for fixing polys. It doesn't always improve things but at least your object is starting out on the right foot.

Radiosity Cache & Screamernet has been a major problem for me & many others. Let alone if you are only using one computer.

Keep Use behind Test on. RPE of 250 seems too high, around a 100 should be enough, Angular tolerance I usually have around 20, Minimum pixel spacing always on 1. Since you are doing a fly through Multiplier should be left on a 100.

Baking the Radiosity I usually run a camera around the object &/or along the camera path at double the resolution every 30th frame. Then at normal camera resolution every 10th frame. Then every frame at normal resolution. I can do every frame because the i7 & x55/56 CPUs are so quick with radiosity compared to previous CPUs.

If you have something moving but it's not casting different shadows through the movie you can exclude that item from the radiosity. If you need the radiosity for that part you can have a duplicate part with say a plain surface & have this seen by radiosity but not seen by camera. Also make sure you have the Rays & Shadows set correctly.

Also have you baked some blotches into the Radiosity.

Do you really need Mont Carlo, for my architectural models I only use Final Gather.

Danner
12-11-2011, 03:43 PM
There is another way to achive good looking radiosity with low rendering times, use a high RPE (1000 or so) and a min pixel spacing that is a higher (around 15). If the scene is complex, Monte Carlo is usually faster than Final Gather. This are my prefered settings now. The radiosity cache pass is usually close to an hour for 1000 frames then each frame renders for around 5 min.

HolyMonkey-
12-12-2011, 10:53 AM
Locked means that LW has to use the radiosity that has been baked & not change it.

Is your object nice & tidy, joins welded, no non planar polys? LWCad has a great tool for fixing polys. It doesn't always improve things but at least your object is starting out on the right foot.

Radiosity Cache & Screamernet has been a major problem for me & many others. Let alone if you are only using one computer.

Keep Use behind Test on. RPE of 250 seems too high, around a 100 should be enough, Angular tolerance I usually have around 20, Minimum pixel spacing always on 1. Since you are doing a fly through Multiplier should be left on a 100.

Baking the Radiosity I usually run a camera around the object &/or along the camera path at double the resolution every 30th frame. Then at normal camera resolution every 10th frame. Then every frame at normal resolution. I can do every frame because the i7 & x55/56 CPUs are so quick with radiosity compared to previous CPUs.

If you have something moving but it's not casting different shadows through the movie you can exclude that item from the radiosity. If you need the radiosity for that part you can have a duplicate part with say a plain surface & have this seen by radiosity but not seen by camera. Also make sure you have the Rays & Shadows set correctly.

Also have you baked some blotches into the Radiosity.

Do you really need Mont Carlo, for my architectural models I only use Final Gather.

You mind giving me an indept view on radiosity here or PM? Some tips and tricks you use?

I quite dont get your camera trick hmm.. Doesnt it bake radiosity through the camera?

Danner
12-12-2011, 12:29 PM
Radiosity is baked based on what the camera sees, but it stays "glued" to your surfaces once it has been cached. So it doesn't matter what camera you use to calculate the radiosity. A higher resolution camera will get more samples and details, that's why he does a double rez pass, and even tho it takes longer it works on existing cache so the first one will be the slow one, the rest will be much faster.

There are different aproaches to getting good results but this guide is great for pointing out what each thing does.

http://www.except.nl/lightwave/RadiosityGuide96/index.htm I guess we did't point you to it before because we assumed you had seen it.

Greenlaw
12-12-2011, 01:13 PM
Baking a radiosity solution doesn't necessarily speed up rendering a scene. In fact, depending on how your camera is moving and what it reveals throughout the animation, Baking can actually increase your render times significantly. This has to do with how baking works and knowing when to use it and when to avoid it.

For answers, I highly recommend reading the 9.6 Radiosity Guide by Except mentioned in the previous post. This is the definitive guide on using Lightwave radiosity and it can explain almost any question you have about the subject.

(Newtek should purchase this document and include it as part of the official manual--I can't count the number of times I've had to reference it. And while they're at it, they should purchase Execpt's excellent AA guide too.)

G.

JonW
12-12-2011, 01:37 PM
The Radiosity file, you can keep adding to it. The reason I do each 30th or so frame around the object is that if you are going to have a continuous loop in your movie. Sometimes I found that the radiosity at the end doesn't quite match the radiosity at the start, you can also first bake first & last frames. Then I just fill in the gaps with more more baking.

You can keep adding to the Radiosity file as much as you want & can do it with different cameras. If you have 3 fly throughs of your scene. You just make sure that for each camera the area of the object is baked. The more that is baked the quicker additional baking takes. You can also over do it & get a really large file.

You can also stop baking & restart with the same or different cameras & you won't loose the baking you have done. Say you start baking & it's taking too long. Stop, change some of your settings & restart baking. As long as the quality of your settings is ok & you are happy with some test renders to start with. You can keep adding to the file. For a typical architectural fly through you don't need a different baked radiosity for each different camera.

You can also bake quickly through the scene, then start baking more frames & once you are part way through. Get another instance of layout to start rendering only up to the frame number that was done when you started rendering with the radiosity file (Locked Radiosity only). When the radiosity is done restart rendering & set the First frame to the number you stopped at.

If you are a bit nervous about doing this. Another way to save a bit of time rendering is, once you have baked your radiosity & you are ready to render (Locked Radiosity). Is to fire up 2 instances of LW & load the scene twice as long as you have enough ram (don't save the second scene or if you do save it name it "B" or something different so it doesn't bugger up your primary scene).

On the second instance start rendering from the end so (First 1000, Last 1, Step -1) or do both instances from the start & on the 1st instance (First 1, Last 1000, Step 2), on the 2nd instance (First 2, Last 1000, Step 2). If your fames are taking about 5 minutes to render press F10 on the 2nd instance of LW about 2.5 minutes after the 1st instance of LW. The reason is you are trying to keep the CPUs rendering at 100% all of the time. Quite often 1 instance of LW & the CPUs are around 80% usage, depending on you scene.

HolyMonkey-
12-12-2011, 02:06 PM
The Radiosity file, you can keep adding to it. The reason I do each 30th or so frame around the object is that if you are going to have a continuous loop in your movie. Sometimes I found that the radiosity at the end doesn't quite match the radiosity at the start, you can also first bake first & last frames. Then I just fill in the gaps with more more baking.

You can keep adding to the Radiosity file as much as you want & can do it with different cameras. If you have 3 fly throughs of your scene. You just make sure that for each camera the area of the object is baked. The more that is baked the quicker additional baking takes. You can also over do it & get a really large file.

You can also stop baking & restart with the same or different cameras & you won't loose the baking you have done. Say you start baking & it's taking too long. Stop, change some of your settings & restart baking. As long as the quality of your settings is ok & you are happy with some test renders to start with. You can keep adding to the file. For a typical architectural fly through you don't need a different baked radiosity for each different camera.

You can also bake quickly through the scene, then start baking more frames & once you are part way through. Get another instance of layout to start rendering only up to the frame number that was done when you started rendering with the radiosity file (Locked Radiosity only). When the radiosity is done restart rendering & set the First frame to the number you stopped at.

If you are a bit nervous about doing this. Another way to save a bit of time rendering is, once you have baked your radiosity & you are ready to render (Locked Radiosity). Is to fire up 2 instances of LW & load the scene twice as long as you have enough ram (don't save the second scene or if you do save it name it "B" or something different so it doesn't bugger up your primary scene).

On the second instance start rendering from the end so (First 1000, Last 1, Step -1) or do both instances from the start & on the 1st instance (First 1, Last 1000, Step 2), on the 2nd instance (First 2, Last 1000, Step 2). If your fames are taking about 5 minutes to render press F10 on the 2nd instance of LW about 2.5 minutes after the 1st instance of LW. The reason is you are trying to keep the CPUs rendering at 100% all of the time. Quite often 1 instance of LW & the CPUs are around 80% usage, depending on you scene.

I never thought you could get this indepth on radiosity, thanks man. Do you have any say ont he different modes? Directional rays, volumetric light, AO etc in the GI solution menu?

JonW
12-12-2011, 02:43 PM
Radiosity is very scene dependent, so lots of trial & error. The best thing to do is as you build your objects/scene is do a lot of test renders. You can set the camera at 50% or 25% & lower the AA to speed things up & get a feel if your radiosity is looking ok. Or render overnight when you are getting towards the finish of building your scene to see if your setting are ok. You will have to re-bake for the final scene but by now you should start getting a feel if the setting for your scene are working.

Another thing is to set global radiosity figures very low & use higher figures for the individual objects that need to be good quality. A typical situation is an architectural model with a stack of trees. everything in the scene is low including trees, & the building is higher, with key parts of the building higher still.

The thing you are trying to do is get away with the lowest possible settings for a quick render but high enough that it's doing a good job, an animation will need higher settings than a still because all the frames are interdependent with settings. & it all goes together with AA, AS, motion blur, Ray Recursion Limit, area light quality & the rest!