This tunnel is meshed from a set of point clouds in 3DReshaper. The individual point clouds were containing a lot of details. But there were some errors between some of the point clouds.
The color shows a color map inspection between the mesh and the point clouds: - green area have deviations < +/- 2cm - yellow areas have deviations > 2cm - cyan areas have deviations > -2cm - red areas have deviations > 5 cm - blue areas have deviations > -5 cm - grey areas are areas on which no point are projected
The biggest deviations are located in the areas where the point clouds did not overlap correctly.
Looking from the bottom of the mesh, you can see some grey areas which actually are the scanner positions!