ASPRS LAS Specifications 1.4 - Class 18

[André Loffet]

Hello everybody !

I understand the definition of class 18 (“High Noise”) of the ASPRS LAS Specifications 1.4. as points in the air (high), and unwanted or without significance to the DTM or DSM, e.g. :

birds, smoke from fires, cloud, water vapour from cooling towers, ...(maybe even UFOs !).

Is this correct ?

[Evon Silvia]

Hi Andre,

That's correct. High noise is essentially sourced from insubstantial or nonexistent features - i.e., features that will not be detected by a subsequent survey, even if it occurs later on the same day. If they do not represent real objects (e.g., interference from highly sensitive SNR settings) then they may also be flagged as Withheld.

Relevant discussions with the LAS Working Group are available here: 

• High noise vs. low noise: https://github.com/ASPRSorg/LAS/issues/74
• Withheld bit: https://github.com/ASPRSorg/LAS/issues/90
  

Feel free to contribute your own input.

Note that High Noise might not include temporal/mobile yet real objects such as cars on a road. I'm not aware of a "normal" class for those features, as interest in those features can be application specific.

Evon

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Evon Silvia PLS QSI Solutions Architect ASPRS LAS Working Group Chair 1100 NE Circle Blvd #126, Corvallis, OR 97330 D: 541-249-5818 | E: esi...@quantumspatial.com

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