In parsing scans in a range-grid format, our code expects the .ply file to have the following format:

• obj_info num_cols <number of columns in grid>
• obj_info num_rows <number of rows in grid>
• element vertex <number of valid vertices in grid>
• property float x
• property float y
• property float z
• property uchar red
• property uchar green
• property uchar blue
• element range_grid <number of grid cells (num_cols x num_rows)>
• property list uchar int vertex_indices

If a grid cell does not have a valid vertex associated to it, the count of the number of elements in the list of the associated vertex_indices should be 0, otherwise it should be 1.