Importing point cloud is incomplete

Problem

Importing a point cloud (LAS 1.2) into Trimble MX software stops early, resulting in an incomplete point cloud.

Solution

While importing the generated .las file into TMX, the process is limited to the number of point records written in the header. The following points are missing and cannot be imported.

Export the point cloud to LAS 1.4 (which has a higher limit), or split the exported file in two or more LAS 1.2 files.

Problem Details

The header in the LAS file contains metadata including Number of point records which is used by the software to import the indicated amount of points. In the case of a LAS 1.2 format, this field value has a size of 32 bits and it is unsigned long type. This means that the highest value for it is 4.294.967.296 point records (2^32). However, sometimes a LAS File has more points, for example 5.195.487.572 points. Exporting such a big point cloud into LAS1.2 format, the third-party software (Ri-Process, Riegl) tries to pass this value into the 32-bit, but this is not possible, and it produces a data overflow. In this example, the header contains 900.520.276 as the Number of point records, which is in fact the number of points in the file minus the maximum value (5.195.487.572 – 4.294.967.296).

Below are the records of the log file when this error occurred:

61261:t324197223: [HeaderRecord] : File length is 145473653504 (M:\2019-06-26_ NOR_ERTMS_Grong-Bodoe-2_(Nordlandsbanen)_MO_MM_ML_workspace_20190917\lasers\L1 - Scanner 1 - S2223535_20190626-052647_0004.las)

61262:t324197223: [HeaderRecord] : Record data start offset is 1488

61263:t324197223: [HeaderRecord] : Record data end offset is 145473653504 (data size 145473652016)

61264:t324197223: [HeaderRecord] : Record length is 28

61265:t324197223: [HeaderRecord] : Record count is 900520276

...

2383:t325305144: [OPCWriter] : Writing block 6700 (at point 886684167)

62384:t325312238: [OPCWriter] : Writing block 6800 (at point 900509214)

62385:t325312551: [OPCWriter] : Level0 had 900520276 source points

62386:t325312551: [OPCWriter] : Level0 has 6816 blocks

62387:t325312551: [OPCWriter] : Level0 has 5746165 tiles

Related Products

Trimble MX software

Support Reference

00098303

Last modified

September 2020