Wednesday, July 27, 2011

GPS Video Overlay

Here are the results from my research into ways to overlay GPS information onto video. I have an underwater camera mounted on a frame which I drop to the seafloor to take video. The video signal is a live feed from the seafloor, sent to a tape recorder, a dvd recorder, and then to a monitor for display. The GPS signal is being recorded from a unit on the ship. My goal is to overlay the GPS information onto the video. GPS signal is NMEA over RS-232; video signal is composite.

Current method:
SeaVision, SeaTrak. This is fine but the font is big. My unit is between 5 and 10 years old, and the company told me the newer versions have a smaller font. Very simple.

Others that might compete:
Horita, GPT-50. More flexibility in what information is overlaid on the video. Overlay up to 9 lines of 20 characters each of text including Time/ Date and GPS Lat/ Lon coordinates. Heard it's hard to set up but great once done.

Outland Technology, 5000A. Looks a lot like the SeaTrak but the font appears smaller in the online images of the output. Very simple.

Black box camera GPS overlay. Has GPS and depth, can also hook up a ps/2 keyboard to input user-defined text. Font and character size fixed.

Possibilities, but not right for my application:
Intuitive Circuits, Geo Stamp. A GPS antenna attaches to it and overlays the data onto video. Doesn't take the RS-232 string.

Video Toolbox software – this handles video overlay through a PC. Requires computer, would be downstream of tape so would require the tape recorder to stamp time/date on the image.

CMAP Systems, Write GPS. No longer making these.

DecadeNet, X BOBs - this handles video overlay through a PC. Requires computer, would be downstream of tape so would require the tape recorder to stamp time/date on the image.

Do it yourself:
Arduino, Video Experimenter shield - add the GPS signal to the Arduino RX on the video experimenter shield. Here's a how to. Requires figuring out a junction box for vessel usage.

Conclusion:
Pretty sure I'll just stick with what I have for this year.

2 comments:

Kathryn Ford said...

I'm on the ship now. We decided to not to use a GPS stamp at all. We had two standard def cameras, and I couldn't stamp them both. Since we were dropping at a single spot, I decided just to record the GPS. For the hi def system, I think the only way to do it is to record over the audio channel or do it post processing. Once again, we're dropping at a single spot, so we just recorded the GPS. This does require good notes and time syncing, but it's a simple and effective solution.

Kathryn Ford said...

Seth Ackerman, USGS Woods Hole, showed me a Horita instrument that puts the GPS stamp on the audio channel.