I was just looking for opinions on peoples setup when flying for aerial photo/surveying. What combination of Altitude/front lap/side lap seems to produce the most accurate imagery and elevation data? Thoughts?
Please do not take what I do as gospal, or wven a bmp, but with the size of my sites I am trying to do around 80% front/side and 200-250 elevation. I would like lower, but it becomes a value engineering question…
Thats similar to what I have flown. What are the size of your sites? Also, what do you mean by “value engineering question?”
What kind of accuracy do you get on your elevations at 200-250ft?
My sites are 200+ acres. An example of a small site is: http://drdp.ly/R82dHt
In terms of value engineering, another way to say it is to analyze the additional benefits I wouls gain for increased results. To date my “paid” projects have not required increased accuracy/resolution. With that said as I am getting more into the topo/Cad file tupe deliverable, I intend to increase my overlap and decrease my elevation some. I also am going to be incorperating gcp’s into my flights using known points and my new aeropoints (upon delivery). With this extra attention and increased accuracy, my deliverables will also increase in price
Oh, I see what you mean. Finding that balance is key. Yeah, that is what I’m looking to do as well. Using ground control to get my accuracy in the <10 cm range so that Asbuilts can be generated in CAD software.
very cool, @gryzzlydev - are you thinking in terms of local or global accuracy?
Global. We’re going to have survey grade (sub-centimeter) ground control points to work with. I’ll be flying a 20mp camera at a relatively low altitude with 80% overlap. So I’m hoping we can get the global accuracy really low.
It is important to note that for global accuracy, as it has been explained to me by a PLS, the center of the earth is only tied down to within 3-cm so your global position based offnof gps/satalites/glibalnposition correction systems is limited by this. That is why ground control points are important. In terms of local accuracy there are many ways to get that to the +/- 1-cm range of accuracy.
I wrote a little explainer over here on how overlap is affected by hilly terrain or tall buildings and trees.