In Yswami's thread on Blunder and Error Detection Procedures, there is some discussion on Zenith Angle and Slope Distance, Horizontal Distance etc. Rather than muck that thread up, I'll ask here:
1. If one intends to gather and transfer data via a DC using a raw data format, is ALL the 3D data gathered and transmitted? In SurvCE there appear to be, in "Job Settings", the choice for Vertical or Zenith angles, Horizontal or Slope Distances, etc. but is this just for observing the data on the DC? Does all the data get collected, so that the choice to do a 2D or 3D LSA analysis can be made later?
2. Are there any advantages to doing everything in 3D, whether or not elevation data is needed for a particular project?
> In Yswami's thread on Blunder and Error Detection Procedures, there is some discussion on Zenith Angle and Slope Distance, Horizontal Distance etc. Rather than muck that thread up, I'll ask here:
>
> 1. If one intends to gather and transfer data via a DC using a raw data format, is ALL the 3D data gathered and transmitted? In SurvCE there appear to be, in "Job Settings", the choice for Vertical or Zenith angles, Horizontal or Slope Distances, etc. but is this just for observing the data on the DC? Does all the data get collected, so that the choice to do a 2D or 3D LSA analysis can be made later?
>
> 2. Are there any advantages to doing everything in 3D, whether or not elevation data is needed for a particular project?
I can not speak to item 1 but as for item 2, it is always nice to have the 3D info in hand when the client asks for it later down the road. Also, any time you are working with a projection the vertical data is needed for ground distances.
> 2. Are there any advantages to doing everything in 3D, whether or not elevation data is needed for a particular project?
Since the additional work required to run in 3D is trivial (record all instrument and target heights), what advantage would there be to working in 2D?
> > 2. Are there any advantages to doing everything in 3D, whether or not elevation data is needed for a particular project?
>
> Since the additional work required to run in 3D is trivial (record all instrument and target heights), what advantage would there be to working in 2D?
Yup. I see that. So Part II of the question:
Once you've got 3D data, using Starnet, does using it there make the process any better than in 2D? It seems that in Yswami's case, it was the elevation data messing things up. If he's interested in closing a traverse, does having 3D data in Starnet, help, hurt, or just doesn't matter one way or another for such a task?
3D Data Collection Is No Extra Work For Data Collector
It is however extra Work for the data collector operator. One must measure instrument and rod heights and enter same in the data collector. The data collector records raw data zenith angles and slope distances from the total station and calculates horizontal distances. The total station may also reduce zenith and slope and display horizontal. I am not sure but you may be able to screw your recorded raw data up by changing you raw data setting. If you have elevations on the data collector will store an elevation for each point. If elevations are off the data collector still stores an HI & HR but it may be from a different job, i.e. the last time you had elevations on. You can calculate elevations at a later time, but only if the HI & HR are correct.
I carry elevations for all traverse points. I may or may not store elevations for field points. I use 5.00' height rods as standard procedure, booting the rod when necessary. Since I turn elevations off for reflectorless shots, I occasionally forget to turn elevations back on as soon as I should. Those few elevations I calculate from my raw data.
When I am traversing using multiple tripods I have prism sets that give a measured rod height 0.31' or 0.32' less than my instrument height at that setup. If I am at my new point and forgot to measure my backsight height I adjust per the previous HI. Being off 0.01' either way does not corrupt my data set.
On a regular basis my traverse elevation misclosures are equal to or less than horizontal misclosure.
Paul in PA
3D Data Collection Is No Extra Work For Data Collector
> When I am traversing using multiple tripods I have prism sets that give a measured rod height 0.31' or 0.32' less than my instrument height at that setup. If I am at my new point and forgot to measure my backsight height I adjust per the previous HI. Being off 0.01' either way does not corrupt my data set.
>
> On a regular basis my traverse elevation misclosures are equal to or less than horizontal misclosure.
>
> Paul in PA
Paul:
Thank you. This is all great stuff to consider, moving from the "old ways of the field book" to data collection. I'll probably do most of my next round of field work using multiple tripods, so I am modifying my prism mounts so that their elevation exactly matches the instrument in a tribrach. One less thing to worry about. I think I've seen a check box, either in SurveCE or Magnet (or both), to "use same height for BS and FS" or something to that effect.
It still sounds though, like copious field notes are still going to be a good idea, especially until I figure out what I'm doing with a data collector.
3D Data Collection Is No Extra Work For Data Collector
Once you get used to including the instrument and target heights at the beginning of a set-up, it is not a big deal. If you do not want to be bothered with recording rod heights on side shots as they change, set the rod at 999 feet. You can easily let your software deal with the bad elevations in your data file later.