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About the 'warning', the LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing Return Number and 3 bits for Number of Returns (see in asprs.org, 'LAS 1.2 Format Specification September 2 2008 (PDF)', from page 7 to 10, point data record formats 0 to 3).

3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than 5 return types.

The warning you get is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.

"As I got a warning I wanted to check what was the maximum number of returns the laser software and/or the processing software was capable of recording. Would the warning indicate that a return number would be erroneous?"

The LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing Return Number and 3 bits for Number of Returns (see in asprs.org, 'LAS 1.2 Format Specification September 2 2008 (PDF)', from page 7 to 10, point data record formats 0 to 3).

3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than 5 return types.

The warning WARNING: there is 1 point with return number 6 you got is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.

About the 'warning', the LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing Return Number and 3 bits for Number of Returns (see in asprs.org, 'LAS 1.2 Format Specification September 2 2008 (PDF)', from page 7 to 10, point data record formats 0 to 3).

3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than 5 returns (and return number).

The warning you get is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.

About the 'warning', the LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing Return Number and 3 bits for Number of Returns (see in asprs.org, 'LAS 1.2 Format Specification September 2 2008 (PDF)', from page 7 to 10, point data record formats 0 to 3).

3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than 5 return types.

The warning you get is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.

About the 'warning' part, the LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing 'Return Number` and 3 bits for 'Number of Returns'. 3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than five returns (and return number).

The warning you get is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.

About the 'warning', the LAS 1.2 format has in its section 'Point Data Records' 3 bits for storing Return Number and 3 bits for Number of Returns (see in asprs.org, 'LAS 1.2 Format Specification September 2 2008 (PDF)', from page 7 to 10, point data record formats 0 to 3).

3 bits represents 8 combinations (so, 8 different numbers). This means it is possible to record more than 5 returns (and return number).

The warning you get is from the lasinfo report from LAStools. Martin Isenburg (LAStools dev) explains it in this post:

... . The WARNINGs about return number 6 and 7 usually mean the data was acquired with RIEGL scanner that occasionally generate more than the usual 4 or 5 returns that you get from the common Leica and Optech systems. Originally the LAS format was only designed to have at most 5 returns per shot (Paul Galla from Leica Geosystems was part of the original LAS design team in 2004). However, enumerating returns from 0 to 7 is possible in the LAS format (there are 3 bits) and the 1 to 7 range is commonly used (the 0 is usually assigned only to either synthetic or non-LiDAR points such as those generated by dense-matching ). I should probably reformulate the WARNING to raise less concern.