PBRT安装全攻略

Install PBRT for Windows 7 & Visual Studio 20101.Get PBRTDownload from the official website: /downloads.phpChoose prbt-v2-src.zip, for Windows(14MB).Unzip the pbrt archive into a local directory. I'll refer to the fully qualified path to the root pbrt directory (your_local_dir/pbrt-v2) as PBRTSRC_ROOT.Here I choose the directory: C:\pbrt-v22.Build PBRT on Windows Using Visual Studio 20101) Open the src/pbrt.vs2010/pbrt.sln Visual Studio solution file.2) Select either Debug or Release, and x86 (win32) or x64.3) Build the solution.3.Set the PBRT_SEARCHPATH for WindowsPBRT compiles each of its modules as dynamically linked libraries and uses PBRT_SEARCHPATH to find these libraries when running. Create a system environment variable called PBRT_SEARCHPATH and set its value to PBRTSRC_ROOT/bin. You may also find it convenient to add the directory to your system path.Here I set to PBRT_SEARCHPATH to C:\pbrt-v2\bin.PBRT should now be ready to go.4.If you need to modify the PBRT parsing code, follow these steps first:1) Install Bison and Flex programs if they are not already installed.Choose either Cygwin or GnuWin32; either one will work.IMPORTANT NOTE:Do not install under "Program Files" or "Program Files (x86)".The installation path should not contain any spaces. Use C:\cygwin or C:\gnuwin32, for example.Option A: GnuWin32 /Install Bison and Flex via setup packages.Option B: Cygwin </>Install Cygwin with Bison and Flex packages.These may not be selected by default, so be sure to select them.2) Add Bison and Flex executable paths to the system PATH, so that they can be run from any directory or location.a) Right-click "My Computer" or "Computer".b) Click Properties.c) Click "Advanced system settings" or "System Properties".d) Click the Advanced tab.e) Click the "Environment Variables..." button.f) Add the path(s) of the Flex and Bison programs to the PATH variable, under the system variables group box. Use the semi-colon (;) character to separate path items. Example path to add: C:\gnuwin32\bin;g) Press the OK button.h) Press the OK button.i) Either log off and log back on the computer, or restart it for the updated PATH to take effect.5.Set PBRT path for CygwinNow you must modify your PATH and PBRT_SEARCHPATH environment variables so PBRT knows where to look for plugins etc. To do this edit your .bashrc file (in your Cygwin user directory, note that if you don't have a .bashrc file you can create one from scratch, or worst case, edit the systemwide .bashrc at /etc/bash.bashrc) and add the following lines:export PBRT_SEARCHPATH=/cygdrive/c/pbrt-v2/bin:$PATHexport PATH=$PBRT_SEARCHPATH:$PATH6.Let’s try a small exampleThere are several example scenes in the folder PBRTSRC_ROOT/scenes (For example, C:\pbrt-v2\scenes in my computer). Also, you can download more scenes from the PBRT homepage /scenes.php.Open Cygwin Terminal, and change to the scenes directory and render the bunny by writing:$ pbrt bunny.pbrtRemember that rendering is a time-consuming task.After the rendering have been done, you can now visualize the image by converting the *.exr format to *.tiff format by writing:$ exrtotiff bunny.exr bunny.tiffPBRT is a physically based renderer, thus it generates High Dynamic Range images. In practice the pixels’ values stored on the output file have floating point values that can range from 0 to any maximum number. To visualize the image using exrtotiff to convert the High Dynamic Range format to the TIFF format, you can adjust exposure by setting parameters.The quality of the rendered image depends on many parameters and on the particular choice of algorithms used. The noise you see on the image depends, among others, on the number of samples, i.e. rays, taken per pixel.Edit the Bunny.pbrt file such that it uses the “path” surface integrator and only shoots 4primary rays per pixel. You can open the Bunny.pbrt file by Notepad and replacethe lines:Sampler "lowdiscrepancy" "integer pixelsamples" [32]in the original file, with the following lines:Sampler "bestcandidate" "integer pixelsamples" [4]SurfaceIntegrator "path"Render the image again and visualize it. The first thing you will notice is that the image is full of noise. Variance, or noise, can be reduced by increasing the number of samples taken. Unfortunately, rendering time increases linearly with the number of samples but variance reduces with the square of the number of paths. In practice, you’ll have to take 4 times more samples to have half variance.Figure 1. The left is the image rendered with original file bunny.prbt, the right one is the image rendered with uses the “path” surface integrator and only shoots 4 primary rays per pixel.。