Elevation Issue

Capture images with Autel EVO II RTK Enterprise drone.
Drone RTK connected to UNAVCO CORS station 10 km away.
Images HAVE extensive EXIF data including WGS84 lat, long and ellipsoid elevations. EXIF data includes attributes GPS Altitude, GPS Latitude, GPS Longitude, GPS Position, Absolute Altitude, and Relative Altitude along with GPS Longitude.
All images are captured in FIX mode.
Desktop computer, Windows 10 Pro, Chrome, WebODM LIghtening

After uploading images only, the Default option was selected. Data set processed to completion. Results x,y values in UTM 11 N with ellipsoid heights in meters for Altitude/Elevation.

To convert ellipsoid heights to survey feet, loaded the DSM to QGIS and added an appropriate Geoid height to compute Orthometrid heights in meters, and then multiplied the meters by 3.2808334 for survey foot values. Contours were generated by QGIS from the survey foot input.

The resulting values contours were checked against control points established by RTK GPS utilizing the same UNAVCO CORS station. Contour values varied from the surveyed point value by up to 3 feet.

4/18/2022, 9:19:24 AM Task processing: Olivas default options only

Download Results Details

Transaction ID: 65ac99a5-2053-4814-94e0-5636fc4d2532

Images: 154
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How can the results be improved?

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Welcome!

Were you stopping for each photo?

No, the drone flew non-stop from start to finish. Checking the Exif data on several images, the time-stamps indicate continuing motion.

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Have an idea of average exposure time? You might be getting rolling shutter distortion.

In a random sample of sequential image pairs, the exposures are two to three seconds apart. Exposure times per image are about 1/800 of a second. Aircraft speed is logged as 4.99 meters per second (about 11 mph), a speed selected to avoid potential issues with “rolling shutter distortion.” Given the numbers above, the aircraft would move approximately 6mm while the shutter was open.

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That’s the thing about rolling shutter distortion, the readout time is what is important, not the exposure time, which is more important for motion blurring.

Do you know the readout time of the sensor in your Autel EVO II RTK Enterprise drone?

As an example, which is not necessarily the case here, if readout time is 50ms, then rolling shutter distortion would be 250mm.

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