The 50k OBJ is the low-resolution file that is specifically used for the Matterport Showcase. This version has some of its finer detail stripped out and compressed to reduce the overall size of the scan to ensure the showcase loads quickly and stays responsive. By comparison, the high resolution OBJ keeps all of the original detail of the scan. As a result, the file size is quite a bit bigger.
Comparing the different OBJ versions?
To understand the difference in resolution between the two file types, we used a recent scan of a mechanical plant room. This scan contained a considerable amount of fine detail such as mechanical pipework, cable trays, valves, duct work.
Comparison using FBX/OBJ
It’s possible to see some visible differences in the resolution between the two images below. You might notice some patches within the left image are a bit blurrier and less defined than the right image. However, you will also notice that key detail is still visible within the lower resolution version – i.e. mechanical pipework, cable trays, valves, duct work can be clearly identified in both versions
Another comparison was done by converting to point cloud using our Matterport to point cloud conversion tool. Both versions were then opened using Autodesk ReCap 2016 and compared side by side (see below).
The difference in resolution between the two versions is even less noticeable when comparing point clouds. The right image appears a little more crisp in some areas, but in general the level of detail appears to be fairly similar between the two. Again, you will notice that key detail is still visible within the lower resolution version – i.e. mechanical pipework, cable trays, valves, duct work can be clearly identified in both.
To quantify the difference between the two OBJ file versions, we performed some analysis. This analysis considered +200k randomly sampled feature points in the low resolution OBJ file and measured how far it deviated from the corresponding feature point within the high resolution OBJ file (see below) – the results were surprising.
In the end, it really comes down to your specific use case. Using the above example, if you are using your Matterport scan to model mechanical pipework, cable trays, valves, ductwork etc. – the low resolution OBJ file should certainly be sufficient. If on the other hand you wish to model finer detail, the higher resolution OBJ file might be a better choice.