georeferencing trouble

[jude-mb]

i'm following the manual and having some trouble using HDMapping to georeference Mandeye-MR data using GNSS files

open multi_view_tls_registration step 2
open session (from step 1)
load all .gnss files
where is "show GNSS correspondences" button?
click Manual Loop Closure
where is "initial poses as motion model" button ?
Compute Pose Graph SLAM
export as Global Scan
output .laz file is not georeferenced?

[JanuszBedkowski]

Hi I am working on release 101, lets back to this issue ASAP

[jude-mb]

Hi, I am still having this issue with v101

[jude-mb]

when loading GNSS files i received error pj_obj_create: Cannot find proj.db and fixed by copying a valid proj.db (from an OSGeo4W proj install) into the same folder as multi_view_tls_registration_step_2.exe and proj_9_3.dll - not sure if this is expected?

[jude-mb]

also the issue does not seem to be the GNSS file themselves, lat and lon seem correct

[michalpelka]

It should be copied by itself, I am not sure if Janusz added it to release properly. I will check it.
You need proj.db next to exe file on Windows.
Here is my dev build on linux loading NMEA / GNSS using Proj:
https://youtu.be/7aXIvFPzBww

Current startus is like that:

• Proj is available for use both on Linux and Windows and has some great features (e.g. support for multiple coordiante system, currrently PUWG92 and UTM and LLA). Also it is industry standard for dealing with geographical coordinate systems.
• Old, hand-written functions are available and marked as deprecated.
• To use correctly, you need to download chose GPX geoid model, if not, exported data can have incorrect height.
• There is possibility that proj.db is not delivered.

[jude-mb]

Hi, thanks for the video! It was unclear before that i needed to press "save metascan points to ...". I'm still having some issues though. When I save metascan points to WGS84 LLA the laz file is corrupted:

Otherwise saving to PUWG92 or UTM_AUTO or WebMercator works fine.

Converting this to EPSG: 27700 and viewing in CloudCompare with georeferenced ALS data from the UK National LiDAR programme it seems they are vertically misaligned but seem to be aligned in X and Y.

There is only the option to save geoid to WGS84Ellipsoid ...

[JanuszBedkowski]

Hi are You in Oxford?

[jude-mb]

No, I am not XD

[JanuszBedkowski]

Can I consider this issue is solved?

[jude-mb]

There a a couple of issues to solve still ... when exporting metascan points to WGS84 LLA, the output .laz file collapses to a line of points - are you able to fix this issue? Is there a way to add vertical datums other than "WGSEllipsoid" (this is unclear)? Also, working around these issues and exporting .laz as UTM AUTO using .gnss files as shown in the youtube video then reprojecting using a compound CRS (EPSG:32630+4979) the file is hugely tilted compared to georeferenced ALS data ... how can I avoid this?

[JanuszBedkowski]

can You share data and detailed info how to reconstruct problem?

[michalpelka]

Coming back, I've tested UTM, it works fine.
Here is data, if you want to do repro on your side:

Data	Link
Mandeye session	https://drive.google.com/file/d/1Mx_0BWuykzY8g-1zdMQteJM0PlxWGtSR/view?usp=sharing
UTM Airborne Lidar	https://drive.google.com/file/d/12YZuES_bgDDc_EgprU7VwceF9iLGaH58/view?usp=sharing
Puwg92 Airborne Lidar	https://drive.google.com/file/d/1WeId-nfs0hMGOkfG8-_mogK5M3iQWMAl/view?usp=sharing

You can add vertical datums, simply download https://github.com/OSGeo/proj-datumgrid/blob/master/egm96_15.gtx and place next to EXE - it should be listed:

I've converted Airborne Lidar from Polish national system to UTM and used SaveMetascan in UTM_AUTO with geoid egm96_15.gtx. Results looks fine:

The WGS84 export works fine, but this data won't be visulaized since they are not Cartesian. X and Y are degrees, Z is meters. It will be rendered as line, box dimensions for WGS84 LLA makes total sense:

I will remove this export, since it confusing and adds no value.
I think except this LLA, georeferecing works as expected.
Note that you can probably export EPSG:32630+4979 ( it is British national system, isn't it?). Simply add it to

std::vector<Eigen::Vector3d> GNSS::CRTConvert(
    const std::vector<Eigen::Vector3d>& llaPointcloud, const std::string targetCRT, const std::string geoid)

[michalpelka]

PR to remove this export : #459