so, I created an iphone app a few weeks ago that can be used like a transit level. here is a little story and a video. I'll add more as I overcome my camera shyness.
This all started a few years ago, I had the idea and started building the app on my own, but I never finished it. The idea rattled around in the back of my head since then, but once I was laid off it all came rushing to the foreground. I had recently listened to Paul's podcasts on residual income and figured I could get a little going with the app. Originally I was going to focus on Permaculture and swales, so i called it Swale Builder.
Once I had a working model of the app it became clear that it could be used for WAY more than just swales. So I changed the name to Sight Leveler since its really a sight level (hand level) like this:
If the app is just hand held its a little fiddly to keep it accurate. Just like the hand level above. So I mounted my phone on a monopod - think wooden stick and rubber bands - then i could make much more accurate measurements.
It works by using two sets of crosshairs and the camera. The camera feed is on screen with the crosshairs, one set of crosshairs is fixed and doesn't move. The other set 'floats' around getting information from the level built into the phone.
When the two sets of crosshairs are aligned, then whatever is in the crosshairs is level with the camera lens.
When I mark contour lines with the app, I drive a stake in the ground that is taller than the phone and monopod. Then I mark the stake right at the camera lens. Now there is a point of reference to aim at. Walk 10 or so feet from the stake and point the phone camera at the stake. Move the monopod up or down the hill and align the crosshairs until they are level with the mark.
Here is a graphic I made that shows the steps:
This is a video that I made for making a level grade line between two points:
I will come back and add more images and videos of the monopod and how the crosshairs work.
Here is a link to the apple store if you want to run out and buy it right now, its $3.99 and I'll be adding more features like setting the slope and degree display.