What exactly is the difference between photo textures and scans?

Easton

I know this probably sounds stupid, but what exactly is the big difference between photo textures and PBR scans? 

I know that scans have more detail, but how exactly? I would like to incorporate them into my workflow soon but am not sure if it is worth the extra headache of creating a decal of say a road line or just taking a photo.

Eric Chadwick

Scans usually capture more than just surface color... reflectance, normal, displacement, etc. And the color is often calibrated so color temperature and brightness are uniform

Photo textures only capture color, and are mostly not calibrated.

m4dcow

To add to what Eric said, there are also different ways to create scans. Sometimes it is the photogrammetry method of taking multiple photos at different angles and using those to generate geometry and textures. Then there are methods where you take multiple photos from a single point, but lit from different angles which is kind of the reverse of the previously mentioned technique. Allegorithmic built some tools into designer for generating maps from these types of photos. There are also techniques like cross polarized lighting to derive albedo and other sorts of maps.

Axi5

They're related but not quite the same when it comes to context. The guys above have it right. 

A scan is an analytical piece of data, the photo is the method in which to capture it. 

Technically speaking, photo textures can be considered scan data if the photographer had some defined real world values to compare against and prove the data is correct. 

Colloquially speaking photo textures aren't scan data because they usually don't take this information into account. 

Easton

hmm, so if I wanted to have accurate, or more accurate textures or decals then scanning is the better option. What program is recommended for doing this, and how many pictures would be recommended for an average texture?

I read somewhere that you need to basically make a grid then take photos of say 10 square meters but you may only use 1 meter taken from the center, why is it done like this? From what I understand I would have to either get up early in the morning or wait for overcast then go out and take photos. I was thinking instead of creating decals by hand it may be easier and look better to just scan what I need.

What kind of camera is best for creating scanned materials, I have this camera: https://www.bhphotovideo.com/c/product/1135402-REG/canon_9126b069_eos_rebel_t5_dslr.html/?c3api=3679,bing,2763659969,4585581963538020&msclkid=4806ab81e9731534ef41f1150d533414 

Would a camera like this be good for photoscanning?