Build material particle optical property identification

A method comprising:

• accessing, by a processor, a stereoscopic three-dimensional (3D) image of a layer including solidified build material particles;
• identifying, by the processor and from the stereoscopic 3D image, a location on the layer of build material particles having an optical property that is outside of a predefined threshold range;
• based on the optical property at the location being outside of the predefined threshold range,
• determining, by the processor, a height of the solidified build material particles at the location on the layer from the stereoscopic 3D image;
• determining, by the processor, a probable cause for the optical property from at least one of a value of the optical property and the determined height of the fused material particles;
• and
• based on the probable cause for the optical property, outputting, by the processor, at least one of an alert or an instruction to correct a condition in solidifying build material particles in a future layer.

A three-dimensional (3D) fabrication system comprising:

• a spreader;
• forming components;
• a processor to:
• control the spreader to apply a layer of build material particles in a build zone;
• control the forming components to solidify build material particles in a selected area of the layer;
• access a stereoscopic 3D image of the layer;
• identify, from the stereoscopic 3D image, solidified build material particles at a location on the layer having an unintended optical property;
• determine a modification to a condition of solidifying build material particles in a future layer of build material particles based on the identified solidified build material particles at the location having the unintended optical property;
• and
• implement a solidifying operation on build material particles in the future layer according to the determined modification.