Bullet Posted February 18, 2009 Share Posted February 18, 2009 First, I'd like to say that this site rocks as i visit it daily for tips, tricks and inspiration for my own work. I'm currently a Vray user but am trying to learn how to use Mental ray so I can properly compare the two engines in terms ease of use and render quality. My problem is that I have an exterior scene comprised of a hotel, grey block "filler" buildings and a site with some entourage. The site is xref'd into the hotel file where all the lighting and camera work is done. I have mental ray using only final gather and i don't have global illumination turned on. When I render the image i can see that there are missing buckets during the final gather calculations and when the final rendering process starts it ignores all the areas that the final gather map has missed leaving me with a final image that contains a bunch of black squares. I am currently using the draft final gather preset with no custom changes to any of the final gather options. Also the render size is 3000x1800. Any help would be appreciated. Link to comment Share on other sites More sharing options...
mattclinch Posted February 18, 2009 Share Posted February 18, 2009 in the render setup dialog box, under the processing tab, set the memory limit at the top to the value of your RAM and see if that helps. Link to comment Share on other sites More sharing options...
Bullet Posted February 18, 2009 Author Share Posted February 18, 2009 Thanks for the quick reply Matt! I'll give that a shot when i get home tonight. Link to comment Share on other sites More sharing options...
mattclinch Posted February 18, 2009 Share Posted February 18, 2009 i'm sorry Bri, i must be confused, i was under the impression that if you are NOT using Placeholder Objects, and the scene geometry is not able to be cached using a value of RAM up to the set memory limit, mental ray will steal memory from caching texture maps, causing black buckets? I have defaultly preset MR to use 15gig of ram, and have never had dropped buckets or trouble caching models, even 10mil+ polys. In what way is this bad? Link to comment Share on other sites More sharing options...
mattclinch Posted February 18, 2009 Share Posted February 18, 2009 ok, so not ALL your RAM as i originally mentioned, but surely a value just under your currently available free RAM? i am still confused as to why it is bad practice to use a larger memory limit? - the caching/flushing/caching process simply adds to render time, so why not use as much of your RAM as you have available? Link to comment Share on other sites More sharing options...
mattclinch Posted February 18, 2009 Share Posted February 18, 2009 ah ok. might have to check out some mentalboutmax mental ray tutorials! Link to comment Share on other sites More sharing options...
Bullet Posted February 18, 2009 Author Share Posted February 18, 2009 Does this mean that by setting that limit it will not help my issue with the missing buckets during the final gather rendering process? Is there a solution for this issue? I've been searching around and can't seem to find a solution. Link to comment Share on other sites More sharing options...
Bullet Posted February 18, 2009 Author Share Posted February 18, 2009 Thanks Brian, I'll look into lowering the fg settings. Link to comment Share on other sites More sharing options...
Tommy Burns Posted February 18, 2009 Share Posted February 18, 2009 I had this problem myself a couple of times a while back. The first time I put it down to texture maps they where just too big. When I changed them to a smaller size it worked. The next time it happened I put it down to either my system being too old or the size of the file. How I got around it for that project was to restart the pc and only open max. You seem to know how to keep scenes tidy as you said you used xref's maybe go down the route of saving the FG first at a lower resolution. Then higher the resolution and use only the read only (fg freeze option). I haven't seen much difference in quality doing this yet. It would be nice to find the actual fix or correct thing to do, maybe someone knows but those are just a few fixes i've used. Hope this helps! Link to comment Share on other sites More sharing options...
Bullet Posted February 19, 2009 Author Share Posted February 19, 2009 Hi Tommy, Actually you pretty much did the same thing I did at first and that was to restart the computer and just run max for rendering. It seemed to work but there should be a better way to solve this issue. I shouldn't have a problem with ram since I have 3gigs worth and it's not exactly an old computer, plus the scene is rather simple especially compared to the stuff that i normally do. Anyways i'll keep looking into it. Link to comment Share on other sites More sharing options...
Bullet Posted February 19, 2009 Author Share Posted February 19, 2009 Here's the link to the finished rendering. All comments are appreciated. http://www.cgarchitect.com/vb/34761-exterior-hotel.html#post241802 Link to comment Share on other sites More sharing options...
SandmanNinja Posted February 19, 2009 Share Posted February 19, 2009 I've switched from BSP to BSP2 when using a lot of proxies, as my notes (I cannot find the source) says if you have limited memory that BSP2 helps. Bri, can you confirm this? Rendering -> Render Setup -> Renderer (tab) -> Rendering Algorithms -> Ray Tracing -> Raytrace Accelleration [x] Enable Method: BSP2 Link to comment Share on other sites More sharing options...
Bullet Posted February 19, 2009 Author Share Posted February 19, 2009 Brian, I am indeed running a 32bit system with the 3 gig switch on, I actually have 4 gigs of physical memory. Which settings would be the major contributor to ram usage? Currently all the settings are the default ones and the final gather preset is set to low. I don't have that many proxies (probably only 5 or 6). Do I have to lower the max. trace depth in the ray tracer section? It seems a little high, it's set to 6 right now. Sandman, If I remember correctly I've tried to switch from bsp to bsp2 but didn't notice it helping as i was still dropping buckets so I just ended up switching back to bsp. Link to comment Share on other sites More sharing options...
Tommy Burns Posted February 19, 2009 Share Posted February 19, 2009 You would probably get away with using a draft setting for most exteriors I have never noticed any difference. Try bring your trace depth, reflection, refraction down to about 3 you will notice a big difference in speed and minimal in quality. Link to comment Share on other sites More sharing options...
mattclinch Posted February 19, 2009 Share Posted February 19, 2009 Brian, I am indeed running a 32bit system with the 3 gig switch on, I actually have 4 gigs of physical memory. Which settings would be the major contributor to ram usage? Currently all the settings are the default ones and the final gather preset is set to low. I don't have that many proxies (probably only 5 or 6). Do I have to lower the max. trace depth in the ray tracer section? It seems a little high, it's set to 6 right now. purely out of curiosity, what is your current 'memory limit' in MAX, and when you have all your programs open (max (with your scene loaded), internet, email, music player etc) what is your RAM usage, and available RAM? Link to comment Share on other sites More sharing options...
Bullet Posted February 19, 2009 Author Share Posted February 19, 2009 Matt, If you're referring to the memory limit under the processing tab in the render dialogue box than it's 650mb. Is this the problem? I'm not at my computer right now but i'll take a look later to see what the normal ram usage is on my system but it shouldn't be much. Brian, Poly count might have something to do with it but I've never had a problem like that with vray before. Just to get you familiar with my work flow, I do all architectural modeling through ACA (architectural desktop) then i "file link" not xref the cad model into max and texture and light. This way i can make changes on the fly with the model when the architects request it and i just have to reload the cad file in max to get the updates. However I do notice that by doing this the cad file brings in more geometry than it should for example extra caps along the top and bottom of wall sections. I don't think that this is the problem though since I've been using this work flow for several years and this problem is only creeping up when I use mental ray. Thoughts? Link to comment Share on other sites More sharing options...
Bullet Posted February 19, 2009 Author Share Posted February 19, 2009 I haven't tried that but i'll give it a try later tonight. Thanks for the input thus far. Link to comment Share on other sites More sharing options...
Bullet Posted February 20, 2009 Author Share Posted February 20, 2009 Matt, To answer your previous question about how much ram my system uses, it's about 500mb without max running, this is just start up with outlook on. Link to comment Share on other sites More sharing options...
luckymutt Posted February 23, 2009 Share Posted February 23, 2009 Hi. I just read over this thread, and here is a little info/thoughts. That black buckets are indeed indicitive of a memory issue. mr will sometimes be able to calculate the data for for a particular bucket, but hitting a memory issue will cause it to not properly record that data in the *.fgm To address this particular case, all you'll need to do is run off a fgm seperately at half (or even a quarter) the resolution of your final image. In the first post you mentioned that you are rendering out at 3000 pixels across. This winds up being a lot of data to handle for a 32bit machine and it isn't too surprising to get these kind of goofs in the image. If you had an outright crash I would not be surprised. Link to comment Share on other sites More sharing options...
luckymutt Posted February 23, 2009 Share Posted February 23, 2009 Although changing the Res of the FG map can/does make a difference to the quality of the finished FG solution a FG map of 1500 pixels should give plenty of quality. Something I've done (depending on the scene) to deal with this res/quality/time issue: Suppose the OP runs off his 3000x1800 image with the fgm at the same time. He gets an image with Quality 'x' Now say he pre-calcs the fgm at even 800x480. He gets quality 'y' at a significant time savings, but perhaps a noticable difference in quality between 'x' and 'y' NOW...he runs off a fgm at 800 pixels, but this time he bumps up the quality from 'Draft' to 'Medium' or even 'High' The resulting quality 'z' *could* bring him imperceptibly closer (or perhaps even above) quality 'x', along with a time/memory savings. However... it would wind up depending on the materials in the scene, and it would be a case-by-case basis as to how the benifits weigh. I've found if there is tons of refraction going on, then the time/quality ratio will narrow significantly. Although personnaly, anytime I stray beyong the 'Draft' FG setting, I usually wind up tweaking the Density, Rays and Interp. spread anyway. Again...all depends on the scene itself... Link to comment Share on other sites More sharing options...
Bullet Posted February 23, 2009 Author Share Posted February 23, 2009 Thanks for the input Lucky. I'll try running the fgm at a lower resolution and see if that works. Link to comment Share on other sites More sharing options...
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