This is directly from their HW Requirements:
Memory consumption:
The RealityCapture application uses state-of-the-art out-of-core algorithms for almost every task. Therefore, you do not need to worry about computer memory.
You can easily register unlimited number of images/laser-scans on a single machine. However, it requires a specific workflow using components. In such case 16GB should be enough for thousands high (36-80 MPX) resolution images. You can find more information about components workflow in the application Help, section Using components.
To align unordered set of images into one component you will need a certain amount of RAM. The consumption depends on a count of images (irrespective of their size) and a count of features per image. If you restrict the count of features per image from default 40K to 20K, you will double the count of images which can use the same amount of RAM.
Meshing, coloring and texturing are completely out-of-core. Hence you do not need to worry about the computer RAM at all. This means that once you have even one million images or scans registered together, you can create a mesh and a texture on a machine with e.g. 16GB of RAM without any performance loss.
Its not about the preselector settings, its all about How many images and the features per image.
If you have 16gb of ram and 1000 images, dont go over 80k for features per image. Using 32GB of ram I run 80k features per image on 2000 images.