[BUG] Incorrect measure with 'measure distance tool'

[singerat]

At first... i am not fluent in english speaking/writing, please consider that.
Describe the bug
When i use the 'measure distance' tool in QGISFMV player with my data, the value seems incorrect.
And if i use the same tool on the sample data provided (https://all4gis.github.io/QGISFMV/) the measures seems incorrect too.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'https://drive.google.com/open?id=1-B2uaW7_cfYZohZYFozrgBhIaztI1MSP'
2. download DJI_0047.MP4 and telemetry.csv in the DJI directory
3. Launch QGIS with FMV
4. Click on 'Create MISB File'
5. Choose as input video file : DJI_0047.MP4
6. choose as input metadata file : telemetry.csv
7. Click on Extract recordings
8. Click on Create MISB
9. Then double-click on the file in QGIS FMV window to launch the QGISFMV Player
10. Go to 00:00:39 / 01:43:00 you will see a parked car with two men (maybe a jeep)
11. Click on the 'measure distance' tool and try to measure the length of the car
12. When i do this, the measure is around 1.80m (zoom to the car to see the measure)... (changing the coordinate system reference from WGS84 to MGRS has no effect on the measure fortunately !)

Expected behavior
If somenone could help me to fix this, and then i could try to use my own data.

Screenshots
attached, a screenshot of the measure

Desktop (please complete the following information):

• OS: Windows 10
• QGIS Version 3.16.3
• Plugin Version 1.15 (installed from zip)

Additional context
Add any other context about the problem here.

[All4Gis]

The accuracy of the data, coordinates calculations etc. has been improved in version 1.15 https://github.com/All4Gis/QGISFMV/releases/tag/1.15 . However, the measurement of distances and area depends on the tilt of the video. If the video is zenithal they should be more accurate.
I hope someday to be able to work more on this part, but now I don't have more free time, but any help is welcome.

Anyway change WGS84 to MGRS has no effect on measurements

[All4Gis]

Any update @singerat ?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[singerat]

Hello Fran, Please excuse me for the long time without answer...and for my bad english writing :-) I actually try to understand how the QGIS FMV code works for the calculation of coordinates (in longitude latitude) of the corners of image. Attached you will find a schema representing my understanding of this calculations... The scripts involved in my 'analysis' are :  - QGIS_FMV\manager\QgsMultiplexor.py Lines 416 and above (function CreateMISB) for the calculations of frame center latitude and longitude - QGIS_FMV\utils\QgsFmvUtils.py Lines 861 and above (function CornerEstimationWithoutOffsets) for the calculations of valueN and the coordinates of image corners - QGIS_FMV\geo\sphere.py Functions _py_distance and bearing. Lines 48+ and 70+. Here some questions :What is the slant range ? it appears very close to value5, is it true or i am wrong ?When i use QGIS-FMV, the slant range returned value is different in QgsMultiplexor.py and QgsFmvUtils.py.  Is value11 equal to value13+value15+value15 ? And some remarks :The formula for calculating degrees_value seems incorrect, if the camera point straight down (at nadir) then the distance is equal to zero and so it is not possible to apply the formula :degrees_value = degrees(atan(value3 / distance))When divide by zero, python returns an error. The formula for calculating "anlge" variable, used for the calculation of the slant range, seems incorrect too.The formula line 418 in QgsMultiplexor.py) is : anlge = 180 + (OSD_pitch + GIMBAL_pitch) i think correct value is :anlge = 90 + (OSD_pitch + GIMBAL_pitch) otherwise if the camera point straight to the ground (at -90°), the anlge value is equal to 90 and then the slant range value is a very big number. Thank you for your amazing work ! I hope be understandable. Regards, Le jeudi 3 juin 2021, 05:21:57 UTC+11, Fran Raga ***@***.***> a écrit : Any update @singerat ? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe. [footprint_for_Fran.pdf](https://github.com/All4Gis/QGISFMV/files/6935488/footprint_for_Fran.pdf)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.