Question on simulation of TLS panoramic scanners

simBauer commented 2 years ago

Hello,

How is the support for TLS panoramic laserscanners (vertically rotating mirror with horizontal rotation, e.g. Leica RTC360, Trimble TX6)? The figure by Medic at https://www.researchgate.net/figure/Perfect-panoramic-terrestrial-laser-scanner-geometry_fig1_316990821 illustrates the principle.

I assumed that I can simulate this type of scanner with the rotating deflector type.

In an older issue #141 you already explained that the parameters scanAngleMax_deg and scanAngleEffectiveMax_deg correspond to rotating polygonal mirrors. So for the panoramic scanner I would set these to scanAngleMax_deg = scanAngleEffectiveMax_deg = 360 (similar to the settings of the profile laserscanner RIEGL VQ-450). However, panoramic laserscanners have a limited field of view due to the mounting which results in an conical “empty space” underneath the scanner. So far I realized this by adjusting the parameters for the field of view (verticalAngleMin_deg=-60 and verticalAngleMax_deg= 240 for a field of view of 300°) and “cutting out” the cone underneath the scanner.

Is there a more convenient way to set this property directly for the scanner?

Simone

lwiniwar commented 2 years ago

Hi @simBauer ,

yes, for a laser scanner of the type you linked, the scanAngleMax_deg should be set to 360, and equal to scanAngleEffectiveMax_deg (to mimic a rotating polygon with 0 sides). During the time the mirror points 'downwards' (i.e., into the mounting), no other points can be recorded, so time continues running. So the way you implemented this with the "filter" critera of verticalAngleMin_deg and verticalAngleMax_deg are correct.

If you are not doing it that way anyway, note that you can set these for the survey once in a scannerSettings tag before the legs:

<document>
        <scannerSettings active="true" id="scanner1" verticalAngleMin_deg="-60" verticalAngleMax_deg="240" />
        ...
        <survey name="..." platform="..." scanner="..." scene="...">
        <leg>
            <platformSettings x="-30.0" y="-50.0" />
            <scannerSettings template="scanner1" />
        </leg>
                ...
    </survey>
</document>

So no - this is not possible to set in the scanner XML, but only in the survey XML (but you can set it once there for all legs). I hope this helps!

Cheers, Lukas

simBauer commented 2 years ago

Hello Lukas, Sounds good. Thanks for your support. Cheers, Simone

3dgeo-heidelberg / helios

Question on simulation of TLS panoramic scanners #283