![]() ![]() Carefully selected image configurations could therefore provide new opportunities for improving the quality of photogrammetrically acquired data.I’ve made further elevation accuracy tests recently. This approach is significant because by removing the need for an accurate lens model it effectively improves the accuracies of digital surface representations derived using consumer‐grade digital cameras. Results of the simulation process, the laboratory test and the practical test are reported in this paper and demonstrate that an oblique convergent image configuration eradicates the systematic error surfaces which result from inaccurate lens distortion parameters. Minimising systematic error surfaces in digital elevation models using oblique convergent imagery Also, take a look at the following reference material. Google “Gently Curved, Convergent, Non-traditional Drone Flight Lines”. To avoid this error, it is helpful to fly curved flight lines which mitigate the doming error. This is caused by accumulation of the lens distortion error through the image block assembled during the SfM workflow. ![]() Gonzalo/Remotely Possible: What you are experiencing is the well-know systematic SfM doming (elevation) error experienced when the imagery is captured using traditional (linear/parallel) flight lines. Also check the difference, it might be a difference of only a few cm, or a meter. In fact give that a try, in crease the mapped area and re-export to see if that decrease of elevation is really there. Really what i mean to say is to map a larger area so that you ensure anywhere you are trying to take data from is well within the bounds and wont suffer from decreasing accuracy at the edges where tie points invariably are less. But lets go on the assumption that every thing on this end is fine and look at the maps.Ī couple of things, since this is relative it would be good to know what the range of elevations in the map are (meaning what height is the darkest blue and what height is the red) While the drone does in theory have some more overlap in turns, that doesn’t actually mean you are capturing any new data. One thing you could do to increase the elevation accuracy is to fly at two heights for the one map, giving it some more data to work with. I Tend to bump my side and front lap up some more, but again should not really cause a huge issue. Hey are correct that even without the GCPs you should be getting a fairly accurate elevation (still remember the elevation will have the most error in it height wise) and using GCP will in crease your absolute accuracy but really shouldn’t have a huge affect on the resolution. ![]() I would also take a look at your resolution (how many cm/pixel is the map done at, and the accuracy (RMSE, X,Y,Z) remember that if you are not utilizing a drone with RTK or GCPs with the map your vertical accuracy is not going to be very good ( passable but not survey grade) As altitude is notoriously hard to accurately extrapolate from GPS.Īlso as i am thinking about it, remember that the elevation is being determined from the relative point of take off for the flight, not in an absolute datum like (NAD83). If you are lookign for a tighter absolute accuracy than having at least a few GCP tagged with an RTK GPS will let you verify your map a lot better. This will help to insure enough data points for proper tie points to be created. I would agree with it is always best to capture data that is 10-20% outside of the area where you are looking to produce quality data. Hey i took a look at your elevation and models and nothing looks terribly off, however not knowing what lies outside of the mapped area doesnt really let me see if this slight curvature is due to the actual ground curving. ![]()
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