COPC and LAS 1.5

[wonder-sk]

Now that LAS 1.5 spec is a reality, it would be good to figure out what to do with COPC spec (which is currently tied to LAS/LAZ 1.4):

• is there going to be a new version of the COPC spec that will be compatible with LAS 1.5?

• what are the consequences about the fixed offsets? (the copc info VLR would not start at offset 375 etc.)

[abellgithub]

Ugh. What a terrible solution it was to mess with the header.

[evetion]

Link to the new spec: https://github.com/ASPRSorg/LAS/releases/download/1.5.R00/LAS_1_5_r00.pdf

[abellgithub]

COPC already contains the min/max GPS time fields that were added to the LAS 1.5 header, but they are in a VLR instead of the header. The time offset could be added to the COPC info VLR as well and COPC could ignore LAS 1.5 🤷

[wonder-sk]

The time offset could be added to the COPC info VLR as well and COPC could ignore LAS 1.5

How would that work though? I assume you would use the reserved bytes of CopcInfo struct to store the time offset, but how about existing COPC client software that doesn't know that the time offset is present - wouldn't it read incorrect times?

[abellgithub]

In COPC the empty fields must be 0-filled. I would think that would always work whether you read the field as an offset or not.

As an alternative. the offset field is two bytes in LAS 1.5. In COPC the fields are 8 bytes, so some indicator could be placed in the 6 extra bytes to indicate that the field is valid as an offset.