I uploaded a large model (2.93 GB on Disk) into the iPad. When I try to open it in iRhino, I get “Initializing Rhino” then the app crashes silently
I presume that I have exceed some limits but what are they?
2.93 GB on disk is pretty big.
There are no hard-and-fast limits except those of the device itself. The iPad Pro 10.5 (2017) and 12.9 inch models have 4 GB of memory. Not all of this is available to Apps. In fact, iOS manages how much memory is partitioned out to individual apps and will close an app if it exceeds some limit. I do not know what this limit is and it is not available to iRhino 3D at runtime.
I would recommend keeping your models under 100 (maybe 150) MB on disk. Removing unnecessary geometry from the file can help, but iRhino 3D tries to ignore this and load only what it can display, however, it does have to process the other stuff before it discards it (it never deletes it from the 3dm itself, just doesn’t load it into memory).