Las format definition

The .las and .laz output of SURE is based on the POINT DATA RECORD FORMAT 2,  as specified in the LAS SPECIFICATION Version 1.2 , 09/02/2008
https://www.asprs.org/wp-content/uploads/2010/12/asprs_las_format_v12.pdf

SURE is able to read data up to LAS Version 1.3 and will write point cloud data in LAS Version 1.2

Item

Format

Size

Interpretation

X

long

32 bit

X coordinate

Y

long

32 bit

Y coordinate

Z

long

32 bit

Z coordinate

Point Source ID

unsigned short

16 bit

Base image from matching (0 based index in image list)

Red

unsigned short

16 bit

Red color channel

Green

unsigned short

16 bit

Green color channel

Blue

unsigned short

16 bit

Blue color channel

Intensity

unsigned short 

16 bit 

  • Results/Point_Cloud:

Point precision value that relates to the point depth standard deviation (σ) and the project GSD. The values are computed according to the following formula:

I = (σ / GSD) * 10000 

  • Results/DSM/las (after True Ortho production):

4th color channel (typically Near Infrared, if the input images contain it)

Number of returns


3 bit

For the dense matching the number of returns is equivalent to the number of stereo models. Maximum value of 7 means seven or more.

SURE makes the assumption that after a given number of stereo models (5 to 7), the sample's accuracy does not increase, for that reason we clamp the number of returns to 7

Classification

unsigned char

8 bit

  • Points originating from Dense Matching (real observations): 0 (unclassified)

  • Interpolated points (from DSM Interpolation, only for Results/DSM/las): 32 (synthetic / created, never classified)

  • Correction shapefile points (based on the interpolation from correction shapefile, in Results/DSM/las and in Results/Point_Cloud): 32 (synthetic / created, never classified)

  • Waterbody shapefile points (based on the interpolation from the waterbody shapefile, in Results/DSM/las and in Results/Point_Cloud): 41 (synthetic / Water)

UserData

unsigned char

8 bit

Accuracy (to be determined)