Any user of Bryce with common sense will tell you that the “nano preview” postage stamp isn’t worth a damn! It is too small to see any meaningful detail in it, and you cannot really use it for the “tweak-check-tweak-check” method that most of us use when using Bryce, especially with big files.
Add a HDRI file for lighting or switch on “soft shadows” and then you will see your render times jump from minutes into hours. (or days) A bristlecone pine’s growth now becomes fast compared to Bryce’s rendering speed!
I often use the Light Lab’s Render Options and change the settings in the drop-down menu (that appear when you click on the small white arrow below the Preview Window) and change it to “Render in Scene” to see how my file will look. The preview is double the size of the useless Nano-preview in the Main Editing Window, but you still have to jump back and forth between the Main Editor Window and the Light Lab, and if you have Bryce 7, then prepare yourself of random crashes when you jump between Labs too quickly!
But with the frustrations of using Bryce 7 (a good, but still a Beta product in my mind and opinion) I have discovered a useful little trick that allow you to reduce the render time of your main window to handle quick tweaks.
Take look at a normal render time…36 Minutes! (Time to leave the computer room and go make some coffee, or do some washing or take an afternoon powernap!)
You would have to wait 36 minutes each time you move a light or an object. By switching off the Textures in the render, the render time is reduced.
You can switch on the Fast Preview mode too. This will show you a more complete picture sooner rather than rendering line for line.
The rendering speed is reduced considerably from 36 minutes down to 1 minute 15 seconds! You sacrifice the rendering of textures, but when you are tweaking and changing settings back and forth, time is important, textures are not! Later when you have set your lighting and atmospheric settings just right, you can switch the textures on again for the final renders.
The discovery of this little setting certainly has done my impatient nature a ton of good!
Keep on Brycin’
Other options include reducing the maximum ray depth and if applying premium effects selecting very low values for RPP. It is hard to recommend using soft shadows effects except in conjuntcion with True Ambience. In almost all other cases simulation of soft shadows with additional light sources or using dome or fill light sources is more efficent. And if multiple light sources are employed setting the shadow intensity at 100% will improve render times. Transparent materials and IBL should also be avoided if possible. Where the transparent materials are glass, using IBL as a backdrop without any HDRI effect, just to give highlights to the glass and using a keylight for the shadows often gives better and faster results.