I fly in mountainous terrain and sometimes I can't start at the top of the hill but rather the bottom. However, my survey area may be up the side of the hill in excess of 400 ft above me but thethe actual agl is still well below 400 ft.

So my question is; is there a way to deal with this? I was thinking of changing the home point manually to someplace up the hill but this has obvious issues and I can't seem to do it anyway. Anyone have any ideas?

I don't think your Home Point move would work as I think elevation is measured above the point where you start the motors not above the home point. Maybe you could land half way up the hill, turn off the motors and then turn them on again and take off - not very practical I know and may not work in any case.

I don't really understand your question but I fly in mountainous terrain all the time, I set my altitude limit to the max (500M) and continue up the side of the terrain. I never breach 400'AGL while flying the contour but I may be much higher than the take off altitude.  Are you asking how to breach the 500M max altitude? If so that is a good question that I have no answer for. Ideally DJI GO would not have a 500M max limit for those of us flying in the mountains, 1000M would be more realistic IME as this would take you to max visual range where LOS flying is a pretty much the standard UAV rule. If it is DJI's idea that 500M altitude keeps you in the LOS range than it would also limit you to a 500M max distance from take off point ...which would be horrible.

As was mentioned above,  just set max height to 500 meters.  This will allow you to fly 1640 feet above home point.  As long as your height is no more than 400 feet agl, you are fine.  But if the mountains are more than 1640 feet above you,  you are out of luck.  You will not clear them.  The faa rule applies to agl,  not altitude.

"So my question is; is there a way to deal with this?"
Yes ... the same way pilots of Cessnas do it .. In your head.
Phantoms are just like your average general  aviation aircraft which don't have radar or laser altimeters.
Pilots of those craft have to calculate and judge by eye their aircraft's height above terrain.

Cale262 Posted at 2016-4-9 15:02
I don't really understand your question but I fly in mountainous terrain all the time, I set my alti ...

Good work that does it, thanks.

Kneepuck Posted at 2016-4-10 03:13
As was mentioned above,  just set max height to 500 meters.  This will allow you to fly 1640 feet ab ...

Thanks that's what I was looking for. Indeed many of the slopes are higher than 1640 ft but this works for many situations.

treeboyy Posted at 2016-4-10 09:20
Thanks that's what I was looking for. Indeed many of the slopes are higher than 1640 ft but this w ...

Another point to consider is that if you start too low and have to climb 1640 feet to get to where you want to shoot, don't expect much flying time, as you will use a lot of battery power to get up there. Better to start your flight at a higher altitude.

Geebax Posted at 2016-4-9 19:52
Another point to consider is that if you start too low and have to climb 1640 feet to get to where ...

if you start with a battery at 100% this should be no issue at all. I've tested this myself extensively. treeboyy, just start with your battery at 100% (and it's not a bad idea to have a few extras, if you want multiple shots of different mountains on the same shoot) and you will be fine.

It is an issue; you really do lose quite a bit of flying time.  But if you want to climb 500 metres and on;ly fly around at that altitude for 15 mins, then maybe it's not an issue....

wellsi Posted at 2016-4-11 02:11
It is an issue; you really do lose quite a bit of flying time.  But if you want to climb 500 metres  ...

This is never an issue as my best reveal shots are done in this manner. Climbing through the rocks and crevasses right up and over a peak or saddle to reveal the valley on the other side, this is really a very satisfying technique/shot. I can fly the 4-500M at a leisurely pace from 500-1000m away and get this shot over the top with usually ~80% remaining on the pack and then spend some more time exploring the top and landing with ~30%. Getting up to 500M really doesn't take much at all but sometimes I need to settle for a saddle as the peak is sadly beyond the 500m limit.

Cale262 Posted at 2016-4-11 02:36
This is never an issue as my best reveal shots are done in this manner. Climbing through the rocks ...

Thanks people! I did a test flight climbing to 1400 ft along a mountain side and had plenty of battery for what I wanted and returned with 56% battery. I have, soon to be, 4 batteries and I routinely have to fly multi part missions so that's not unexpected.