Approximating from a Bitmap
As the easiest and fastest method of creating PBR materials this is the way that most people (including myself) create their textures when they start out.
In this part we will shoot a number of overlapping images and stitch them together to one high-resolution texture. We will then edit this texture to make it seamless and finish by approximating the PBR maps for the final material using software. In this example we will go through the creation process of Paving Stones 018, originally released on June 22nd 2018.
This is an older article which uses the software Substance B2M which has since been replaced with Substance 3D Sampler by Adobe.
The shooting process
Once you have found a suitable surface start taking pictures in a serpentine pattern and make sure that there is always enough overlap between the images. ICE needs these overlapping areas to piece the images back together. Here is an example how the pattern should look:
While shooting the images it is also very important to always keep the camera in a 90 degree angle to the ground or wall. The stitching process is only going to work right if the images only show planar motion from one to the other, perspective changes may lead to problems during the later steps. For that reason I would consider a three-legged tripod to be slightly better than a monopod in this use-case.
In the end you should have a couple dozens of images.