Message: Unable to Perform Photon Mapping.

Reference Number: KB-03093
Last Modified: April 17, 2023

The information in this article applies to:

Chief Architect Premier or Chief Architect Interiors


When I attempt to start a CPU Ray Trace, or when a few ray trace passes have already completed, I receive the following message:  

"Unable to Perform Photon Mapping."

What is causing this to occur?


Photon Mapping is an Advanced CPU Ray Trace setting that accurately calculates bounced lighting in a scene. If Photon Mapping is turned on, it may be unable to be performed due to one or more of the following reasons:

  • You have a very large terrain

  • There are fewer than two objects present in the plan

  • A rogue object that is far away from the main structure

Photon Mapping can be toggled ON/OFF within the Advanced panel of the Ray Trace Options dialog.

When disabled, CPU Ray Trace renderings have low quality lighting effects, but generate more quickly. It's recommended to keep Photon Mapping enabled for all interior scenes and disabled for most exterior scenes.


A large terrain perimeter that contains a varying amount of elevation data will prevent Photon Mapping from being utilized in many cases. Lessen the length and width of the terrain perimeter, rebuild the terrain by navigating to Terrain> Build Terrain ,  and attempt to start a ray trace once again.

A rogue object may also cause this error to occur. If creating a Perspective Full Overview causes your structure to appear small on screen, or the view generated appears to be blank, there is a likely chance that a rogue, stray object is present in the plan. To resolve this issue, please see the "Troubleshooting Small or Blank Camera Overviews" article located in the Related Articles section below. Once the rogue object is gone, start a CPU Ray Trace rendering.

Note: Ray tracing is designed to bounce light off 3D objects. If you attempt to ray trace just a single object you will likely receive this error because the photons will not have enough surfaces to complete a pass. 3D objects can include walls, cabinets, doors, windows, along with a variety of other symbols.  


If you're unable to resolve this error, please use the Backup Entire Plan/Layout tool to create a backup of the plan file and all the associated files. More information on creating a complete backup of your file and all of its contents can be found by accessing the "Using the Backup Entire Plan/Layout Tool to Send Files to Another User" resource in the Related Articles section below.

After a complete backup of the plan is created, please send this to Chief Architect Technical Support using the Technical Support Center. More information on the Technical Support Center can be found by accessing the "Using the Technical Support Center" resource located in the Related Articles section below.