# Vray RT not rendering lights in GPU mode. **URL:** \ **Category:** Issues\ **Created:** [May 19, 2014, 9:44am UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855 "2014-05-19T09:44:43Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![johannpascual](https://avatars.discourse-cdn.com/v4/letter/j/53a042/32.png) [@johannpascual](https://forums.chaos.com/u/johannpascual)\ **Post date:** [May 19, 2014, 9:44am UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/1 "2014-05-19T09:44:43Z")
Hello, peeps! I need help… maybe someone has experience on my problem. Here are my specs: Intel i7 - 4770K Gigabyte z97x-ud3h 8gb RAM nVidia GTX 770 2gb - latest drivers (335.23) Windows 7 Ultimate - latest updates SketchUp 2013 Pro Vray v2.0 sp1 RT is fine with CPU mode. Stable and no problems. But when I use GPU CUDA, it doesn’t render the lights. Please see attached. Please help… I want to make use of my GPU to get my money’s worth. ☹ ![VrayRT Issue.jpg](https://europe1.discourse-cdn.com/chaosprd/original/3X/7/3/73c2ab60a31e794a89c6256f5c81eb4f04624d6c.jpeg) ---
**Author:** ![tedvitale](https://avatars.discourse-cdn.com/v4/letter/t/74df32/32.png) [@tedvitale](https://forums.chaos.com/u/tedvitale)\ **Post date:** [May 20, 2014, 1:28pm UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/2 "2014-05-20T13:28:58Z")
What kind of lights are you using in the scene? I see spot Lights, but are you using any other lighting types? If you could send me the file I might be able to take a look at it and see Whats going on. ---
**Author:** ![johannpascual](https://avatars.discourse-cdn.com/v4/letter/j/53a042/32.png) [@johannpascual](https://forums.chaos.com/u/johannpascual)\ **Post date:** [May 20, 2014, 3:08pm UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/3 "2014-05-20T15:08:33Z")
Howdy, Ted! Actually, it doesn’t matter which file it is, everything just comes out that way. It’s fine with CPU rendering or in the final render. It’s just when I change to GPU rendering that it becomes like that. The lights I use are just spot lights and materials with emission lighting. Could it be the drivers? ---
**Author:** ![tedvitale](https://avatars.discourse-cdn.com/v4/letter/t/74df32/32.png) [@tedvitale](https://forums.chaos.com/u/tedvitale)\ **Post date:** [May 27, 2014, 9:25pm UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/4 "2014-05-27T21:25:05Z")
I’m not sure. With out the scene I cant tell what would be causing the problem. I Imagine its GPU being funkie. Ill try and do some testing on my own and see what I can come up with. I doubt its the drivers though. ---
**Author:** ![johannpascual](https://avatars.discourse-cdn.com/v4/letter/j/53a042/32.png) [@johannpascual](https://forums.chaos.com/u/johannpascual)\ **Post date:** [May 28, 2014, 6:05am UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/5 "2014-05-28T06:05:52Z")
Hello, all! I have done screenshots for you all to see. I have placed all the files [here](https://www.dropbox.com/sh/330ulinbhoe9zqg/AAAPJeLwE-afPWr7PD4HDTgRa). Here are the specs: 1. iMac with GTX 680MX (OSX and Win7) 2. Windows 7 with GTX 770 3. SketchUp Pro 2013 and Vray 2.0 SP1 4. Latest Nvidia and Windows Drivers 5. For the RT settings, it’s all default. Notes: 1. For OSX, RT renders look right and you can change the light settings and it will refresh… but the moment you zoom in or change views, it crashes RT. 2. For Win7 on both machines, RT is stable and fast… apart from it not rendering lights correctly. 3. I updated to the latest nVidia drivers and the RT renders seemed to improve. The scene is now lit but the emission materials remain black. ---
**Author:** ![tedvitale](https://avatars.discourse-cdn.com/v4/letter/t/74df32/32.png) [@tedvitale](https://forums.chaos.com/u/tedvitale)\ **Post date:** [May 29, 2014, 7:31pm UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/6 "2014-05-29T19:31:27Z")
So, John, a few things to remember when working with GPU based rendering (and generally a good thing to do when modeling). First, GPU RT Rendering only supports front face objects. So if you are looking at the back side of a Sketchup face, it will show up as transparent. Always make sure all your faces are correctly oriented in a scene. Next, RT GPU does NOT currently support emissive materials (we are working toward supporting it in the future, but for not we don’t). If you are using emissive materials to light your scene (which is a bad Idea in general) RT GPU will not recognize it and it will show up as black in a render. Finally, Omni lights, like what your scene here has, are lighting the scene, but, they will do a poorly job. Id suggest using sphere lights in the future and setting them to invisible. You’ll get a much better result. Hope that helps! ---
**Author:** ![johannpascual](https://avatars.discourse-cdn.com/v4/letter/j/53a042/32.png) [@johannpascual](https://forums.chaos.com/u/johannpascual)\ **Post date:** [May 30, 2014, 1:04am UTC](https://forums.chaos.com/t/vray-rt-not-rendering-lights-in-gpu-mode/49855/7 "2014-05-30T01:04:52Z")
Hello, Ted! Ah, thank you! At least now I understand how RT works. I shall keep your tips in mind.