The origin of the coordinate system of pointclouds

[solmazhajmohammadi]

@ZongyangLi @pless
Right now the origin of the coordinate system is set to the location of calibration object during the first calibration run.

• We can change the origin in the configuration file and reprocess the data. (Requires Fraunhofer to change it)
• Or we can find the exact location by some test scans and define a new origin and add a transformation matrix to the metadata.
  We can go for the second option and @smarshall-bmr can do the scans to find the exact origin.

[ZongyangLi]

@solmazhajmohammadi Thanks! We do not have to change the origin. I just want to make sure:

1. Coordinate of ground surface is constant, it will not change as gantry position z changed;
2. A parameter of converting coordinate into field meters, as y scan distance is 21.8 meters, Y coordinate range in west scanner is from -600 to 21200, can we simply set this parameter to 1000, and assuming that Y coordinate -600 represent field position 0 in Y axis?

[dlebauer]

To follow up on a discussion from today's call, it does not seem that the scanner3DTop metadata includes information about the sensor position or field of view as is the case with all other sensors. It does, however, provide the location of the scanner box:

Here is the metadata from sites/ua-mac/raw_data/scanner3DTop/2016-08-12/2016-08-12__02-24-02-273/b6bc5837-3aaf-4443-8dad-289137e3fa9b_metadata.json:

{
  "lemnatec_measurement_metadata": {
    "user_given_metadata": {
      "experiment title": "Sorghum field experiment",
      "experiment responsible": "to be named",
      "project": "TERRA-REF",
      "instrument": "gantry at Maricopa phenotyping facility",
      "instrument": "field gantry",
      "location": "Maricopa phenotyping facility",
      "date of sowing": "2016-04-19",
      "date of emergence": "2016-04-25",
      "campaign": "seedling emergence and early vigor",
      "mission or scan": "3D Scan Field 0.33MperS"
    },
    "gantry_system_fixed_metadata": {
      "system manufacturer": "LemnaTec Corp.",
      "gantry fixed data 1": "Todo",
      "gantry fixed data 2": "Todo"
    },
    "gantry_system_variable_metadata": {
      "time": "08/12/2016 02:24:02",
      "position x [m]": "48.7015",
      "position y [m]": "0",
      "position z [m]": "1.114",
      "speed x [m/s]": "0",
      "speed y [m/s]": "0",
      "speed z [m/s]": "0",
      "camera box light 1 is on": "False",
      "camera box light 2 is on": "False",
      "camera box light 3 is on": "False",
      "camera box light 4 is on": "False",
      "scanIsInPositiveDirection": "True",
      "scanDistance [m]": "21.8",
      "scanSpeed [m/s]": "0.33",
      "scanMode": "Triggered"
    },
    "sensor_fixed_metadata": {
      "sensor manufacturer": "Fraunhofer-Entwicklungszentrum R?ntgentechnik EZRT, Ber?hrungslose Mess- und Pr?fsysteme, www.iis.fraunhofer.de",
      "sensor product name": "Custom made 3D Scanner"
    },
    "sensor_variable_metadata": {
      "current setting Exposure [microS]": "70",
      "current setting Calculate 3D files": "0",
      "current setting Laser detection threshold": "512",
      "current setting Scanlines per output file": "100000",
      "current setting Scan direction (automatically set at runtime)": "1",
      "current setting Scan distance (automatically set at runtime) [mm]": "21800",
      "current setting Scan speed (automatically set at runtime) [microMeter/s]": "100000"
    }
  }
}

by contrast, the flir camera has a much more detailed sensor fixed metadata field:

    "sensor_fixed_metadata": {
      "sensor manufacturer": "FLIR Systems",
      "sensor product name": "A645",
      "sensor serial number": "13070601",
      "sensor description": "IR Sensor 640x480",
      "sensor purpose": "measure infrared radiation from soil/crop surface",
      "buildin variable optics": "",
      "location in gantry system": "camera box, facing ground",
      "location in camera box x [m]": "0.877",
      "location in camera box y [m]": "1.361",
      "location in camera box z [m]": "0.520",
      "field of view x [m]": "1.496",
      "field of view y [m]": "1.105",
      "output data format": "16bit Grey",
      "calibration available": "calibration parameters from FLIR to convert gray value to temperature",
      "sensor computer interface": "GigE",
      "sensor id": "ir camera box"
    },

[JeffWhiteAZ]

David,
Thanks. It looks like we need to review the metadata for completeness and correctness for each instrument. Stuart, Maria and I looked at the 3D scanner metadata, and I was surprised that there was no data for location within the sensor box. Sensor position in the box is precisely the sort of data that might get changed if we ever modify the sensor box to include new instruments.
Do we have an official metadata expert who cross checks all of the data?

[markus-radermacher-lemnatec]

Due to a glitch in the config file, only a few meta data infos got into the 3D results. This has been fixed now. Solmaz is working on the transformation from the 3D Ply files into the gantry/world coordinate system.

[solmazhajmohammadi]

@smarshall-bmr Do we have the 3D scans with checker boards to find the pointclouds origin and its transformation to the gantry coordinate system?
Probably it is better to do it when the plants are short, otherwise it would be hard and inaccurate.

[smarshall-bmr]

@solmazhajmohammadi I have to build a die to hold the checkerboards at exactly 90 degrees from each other, otherwise the z axis measurement isn't going to be too accurate. That and the field is quite soggy right now.

[solmazhajmohammadi]

@smarshall-bmr any update on this?
@ZongyangLi I think this is what you were referring to, as soon as I get the data, I can give you the transformation to gantry coordinate and origin of point cloud
@smarshall-bmr can you please let me know when you are doing the scan, we can check to make sure we have all the measurements to find the origin relative to the gantry origin