I've read some other posts asking about elevation, and my understanding from them is that if there is a ground based image included in the set, then the elevation data will be fairly accurate. However, in my case with a P3 and a ground level image included, the elevation data is way off. For example, it is showing an elevation of 170' for a spot where the actual MSL elevation is about 75'. The difference in elevation from the take off point where the ground image was captured to this example point is no more than 15'
Can you tell me what am I doing or interpreting incorrectly?
Thx,.
It looks like your exif tags were plowed by Lightroom and it removed the above ground level information from them. This is a common problem with using software to edit the images before they get uploaded.
We highly recommend uploading the images directly as they come from the SD card.
You can search for "Lightroom" in this forum and find out how to fix the issue.
Vui lòng đăng nhập để lại bình luận.
OK, I'll have a look. In the LR export dialog, I do have Preserve all Exif data selected.
Use a good EXIF viewer to check that it was done properly. If the "Software" element says Adobe or anything other than a version number like v01.23.4920 it was likely modified by something.
Had a chance to retest this a bit.
Unfortunately, even without any intervention (editing) of the P3's files the elevation is off on my maps by about 40 to 50 feet. I am including a jpg at the take off location. Is everyone else experiencing perfect elevation readouts on their maps? I'm not sure if the process is looking up the elevation value from the lat/long or what. But it is not working for me.
Maybe the upload dialog could include a parameter where the user can specify what the MSL takeoff elevation was instead
Thanks Guys.
We get the elevation of the takeoff point from a 3rd party service and add that to the AGL value that is saved in the images.
Your most recent job did not have a ground reference image included with it so that is likely the issue. 29 images processed and 29 images uploaded. Generally if you include a ground ref image it will not be included in the processing. The GPS recorded values were about 50 meters off of what the AGL numbers were.
Your upload two jobs ago did have the ground ref image and the elevation we received back from the 3rd party service for the elevation of the takeoff location was 31 meters above sea level. Your 60 meter flight was added to that value.
One thing to keep in mind is that you need to take off from ground location that hasn't been disturbed since around 2002 when most of the elevation data was taken. If you take off the top of a building it will be messed up.
Our Tag Fixer system allows you to put the elevation of the takeoff location into the images.
Hey Ryan,
The last set I uploaded was a repeat. The original map set images were so bad from the "auto" camera settings with no correction that I made some basic edits and reprossessed the map with the edited versions. The elevation layer was off anyway. The test I was referring to was the map before that one which did have a reference image at take off.
I will look for the 'tag fixer' you mention. I missed it. Make so much sense that the user could take responsibility and determine the true elevation at the takeoff point and the processor can do the rest. No third party look up of old elevation data needed. In this case it is quite possible that the topography has changed some from 2002. Many of the sets I have been testing are construction sites after all.
On the editing of image question. I understand the risk of corrupting the exif data if editing is done before upload to MME. Could you perhaps make it possible for after the process is completed, the user could download the geotiff like we can do now. But then edit that image for the desired look and then re upload that edited version to MME to replace the the image on the map without altering the underlying data. Just trying to think of how to not upset the accuracy and still get a respectable looking image.
Thanks again.
re: tag fixer.
I went here: https://www.mapsmadeeasy.com/tag_fixer
This looks just like the usual map creation process that I have been using?
Anyway, I go through "Takeoff info / Select Images/ Test Exif/ Verify Images/ and on the Point use screen, It states that it will take 36 points and that I don't have enough while 500 points are showing available.So I have not gone beyond this step.
They are promotional points, so maybe they cannot be used for this?
Is this utility going to ask me for the takeoff elevation. or all automated. I was thinking it was going to ask me and use that to adjust the elevation exif on the set of images?
I looked at the elevation exif of my images in this set. The takeoff image shows "0" meters. the rest show ~60 meters which is correctly showing their height above the takeoff point. The actual MSL elevation of the takeoff point is 20m. Am I going to be able to specify that in this process?
If you want to edit your source images before uploading them we have a lot of users that can do that. Just make sure you have a copy of the originals with the tags in tact. There are settings in most softwares to not modify the tags. There are a couple of threads on how to do that in here somewhere using Lightroom.
The tag fixer only takes purchased points and asks you for either a takeoff elevation to be entered or uses the lookup value the same as the normal processing. This is generally intended for people that need to fix their tags to be processed elsewhere that doesn't account for the DJI elevation reporting properly.
I'm sure I could figure out how to modify the elevation # in the exif. Do I modify the takeoff photo only, or do I need to change the elevation on the whole set?
And if I modify the takeoff image to the correct msl elevation, how is the processor going to know to not look up the potentially old elevation from your 3rd party service.
Kind of seems like I'm going in circles. Wouldn't it be easier if you added a parameter in the upload process that asks for the msl of the takeoff point and uses that. If that parameter value is not entered by the user then the processor uses the 3rd party lookup routine. ?
I understand you are trying to make this as simple as possible for the masses. But if reliable, repeatable, very accurate results are important, then there needs to be more control IMHO. This puts more responsibility on the user not on you guys.
