Hello there; The kd-tree error is received when the system does not have enough memory to render the defined scene. More RAM is required to render larger sized scenes. Usually this happens when procedural grass is used because the number of surfaces can increase excessively depending on the situation. As a solution, you have no choice but to somehow reduce the number of faces you use in your scene. The solutions that can be applied for this job are: -Reducing your grass density and quality -Defining procedural grass in a limited area close to the camera that will affect the image and leaving the background parts with a plain texture -If you are using a 32-bit operating system, switching to a 64-bit operating system (program 32-bit windows XP' It can also use a maximum of 2GB, 3GB in vista and Windows 7, and 4GB in 64-bit operating systems). Until 1-2 years ago, there was no way to make the rendering process on the graphics cards. Now, CUDA and OpenCL technologies and techniques that use the graphics card for rendering have started to emerge, but they are still in their infancy. For now, it is most efficient to have the rendering process on the CPU, in the medium term, the use of video cards for rendering will become widespread. In the future, ideCAD may also use this technology, but it is still early. For general work, nVidia cards give better results than ATI cards because openGL support is more stable, we recommend nVidia cards for ideCAD. You don't need to buy a super fast card, GT240 and above models are enough to work on average projects. The speed of your processor affects your working efficiency more.