Natural Resources Canada publishes "LiDAR Data Acquisition Guideline" for airborne LiDAR

[Martin Isenburg]

Hello,

I just got an email telling me that Natural Resources Canada has published their "Federal Airborne LiDAR Data Acquisition Guideline". The primary goal of this 63 page document is to provide guidance to the Canadian LiDAR community for supporting the development of national highly accurate elevation products. The approach is to harmonize the requirements of airborne LiDAR collection within the Federal government and across the provinces and territories. The document promotes the acquisition, the sharing and re-usability of LiDAR data - including for wide-ranging projects that overlap many jurisdictions. The guideline is available for download here:

http://ftp.maps.canada.ca/pub/nrcan_rncan/publications/ess_sst/304/304669/gip_117_en.pdf

 

Regards,

Martin @rapidlasso

[Martin Isenburg]

Hello,

My first comment is that I am very happy to see this requirement:

Open Access: Only open LAS format is to be used and no proprietary formats are acceptable. 

My second comment is that I am bit confused by (the wording of) this requirement:

Overlap and Overage: Overlap pulses will be identified as using overlap bit 3 as described in Table 16 in LAS 1.4 – R13 specification. Overage points shall be identified using the LAS overlap flag in all point cloud deliverable which is Class 12. See definition of overage in glossary.

Does that mean *all* points in the overlap area (obviously all overage points but also many of those that are part of the tenderloin) should be given the "overlap" flag but the overage point should be in addition given classification code 12? I would have expected to read that only all the overage points (e.g. those points not part of the tenderloin) are given the (wrongly named) "overlap" flag and that it is advised *not* to make use of the deprecated classification code 12 for that. Below the definitions for overlap, overage, and tenderloin from the same document.

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Overlap:

This is the percent of overlap associated with two adjacent flight lines that happens as a result of the plane flying back and forth through the project area to achieve desired uniform data density and optimal ground cover under canopy

Overage:

Overage corresponds to those parts of a swath that are not necessary to form a complete single, non-overlapped, gap-free coverage with respect to the adjacent swaths. They are the non-tenderloin parts of a swath. In collections designed using multiple coverage, overage are the parts of the swath that are not necessary to form a complete non-overlapped coverage at the planned depth of coverage. In the LAS Specification version 1.4 (American Society for Photogrammetry and Remote Sensing, 2011), these points are identified by using the incorrectly named “overlap” bit flag. See overlap, tenderloin.

Tenderloin:

This is the central part of the swath that, when combined with adjacent swath tenderloins, forms a complete, single, non-overlapped, gap-free coverage. In collections designed using multiple coverage, tenderloins are the parts of the swath necessary to form a complete non-overlapped, gap-free coverage at the planned depth of coverage.