Hi smcmurray,
If you try to process a large number of images and/or high resolution imagery in a single chunk, you may run out of RAM.
Check out Photoscan's memory requirements here:
http://www.agisoft.com/pdf/tips_and_tricks/PhotoScan_Memory_Requirements.pdfTo still be able to process a large project, you could either lower the quality settings or split your project into several chunks. The latter would allow you to compute the dense point cloud for each chunk individually and at the end merge all chunks again.
It is recommended to split the project
after running the photo alignment step using ALL images. Most of the time it is only necessary to split the project to generate the dense point cloud.
Regards,
SAV