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Mapping Elevations Along A River


I have a mapping request along a river for a flood survey, approximately 6 miles in length. How I should set this up with Maps Made Easy? Apart from the logistical problems of staying in VLOS over varying terrain, this is going to take more batteries than I have available in one trip, so I will need to make several trips to complete the flights. Should I create separate missions for different areas, making sure there is an overlap in the batches of photos from separate flights and visits? I will find out how far I need to survey each side of the river, but can you give me any advice or suggestions about this type of project? Ideally I want the drone to criss-cross the river, rather than flying a long way along the river and out of sight! I have read the post about Linear Mapping but not sure of this and how to activate the feature? 


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Honestly that is going to be an issue if what you are in search of is accurate elevations. You can do linear missions if you have AT LEAST 3 passes but even then you aren't going to get great elevation results. 

Mapping around water is always a bit tricky since introducing motion and reflections are a great way to mess things up.

The smaller the chucks you break it up into the more accurate it will be. 

If you are concerned primarily with the elevation numbers I would do it in sections that are no longer than 2 times the width. This does two things: provides extra width which is needed for solid elevation results and limits the length. 

Example: For shooting a 300 meter section of the river you would want the width to be at least 150 meters.

Also, use as close to 80% overlap as you can live with. 75% probably won't cut it unless you are flying pretty high. 

This extra context on the banks will give plenty of looks in the middle of the area and give the best results you can get. 

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