California Surveyors Forums

It has happened to me that while calculating the coordinates for a new job I end up assigning negative coordinates to some points and I don't realize it until I'm at the site. I haven't changed the coordinates and kept working without any problem. I know that in trigonometry you should be careful with negative values, but could cogo programs in data collectors have a glitch ending up giving wrong directions while surveying on the field?
Have you guys had any problem working with negative coordinates?

Since 1999: TDS or SMI on HP - 48, SDR or Husky I have never had any problem working with negative coordinates.

I have been warned against it a few times so I still try to keep them all positive when setting up a job. Horizontal translation or rotation is a simple process in the field if the negative coordinates do trouble you for any reason.

If you work near any major port in California, you will deal with negative coordinates as the ports were set up with old army coordinates. They picked the center point is 0,0 and ran from there. Most software can handle.

The port of Long Beach uses old LA County zone 7 coordinates, or at least they did during my stay there. There are lots of benches there with negative elevation. Having just started working as a surveyor there, I always found starting a level run below sea level to be a real mind blower.

SFO uses 0,0 at the end of our longest runway, so most of our northing values are negative. I haven't experience any issues with it so far.

Old LA County Zone 7 coordinates and bench marks are two different things.

No matter what the starting elevation, it's always PLUS the backsight and MINUS the foresight for the next elevation.

What's tricky is in tunnels when the backsight itself is negative and the foresight is negative too.

Thank you guys for your valuable input. Obviously, I was talking about the local coordinates ,which you definitely can decide to have positive only. It happens that some points far from the property fall in negative territory. I have treated them same as positive coordinates and no alarm has gone off so far.

Old LA County Zone 7 coordinates and bench marks are two different things.

Really?