Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

We have recently purchased some new GPS survey gear (ProMark 500) and we have set up a localization around the town using some of the known survey marks.

While I'm pretty confident that I have got it right so far, I was wondering if anyone had any good tips for setting up a GPS localization. Is there is anything to watch out for, or things I can do to reduce any error.

Also if anyone has any good articles on the subject it would be greatly appreciated, I'm struggling to find anything good on the net.

EDIT: While I appreciate the general GPS surveying tips, I was more interested about Localization in general. Does having localization marks close together negatively affect result. Can you have to many localization marks? Things like that.

share|improve this question
    
Your geodetic device will show an accuracy value at any given time. If it reports "sub-centimetre accuracy" you are doing just fine (doesn't get much better). In light of your recent edit, I would mirror the post by Mapperz. Hit up that manual. –  Dano Apr 19 '11 at 15:46

3 Answers 3

I had the pleasure of working with the foremost surveyor in my community on a few occasions.

He is actually "the surveyor" that businesses & government bring in to fix/correct inaccurate surveys.

In my case, I am not versed in surveying techniques, but I do have the basics pretty well figured out. I have been out capturing x,y,z data for the purposes of watershed analysis, and I've also been out in the field capturing data from test pits and drill collars for the purposes of Hydrogeological studies.

First off, the Geodetic equipment "does" report your accuracy values, so if you're getting sub-centimetre feedback while in the field, you should be just fine. As far as your question regarding "good tips", the most important information that the surveyor mentioned to me was as follows:

  • Find a nice open area for your base station, BUT, also look for an area that will shelter your equipment from the possibility of theft.

What he did, is start at a known benchmark (an IB), then he moved his receiving station to an arbitrary location that provided good communication with the satelites, but was also "not" visible to passers-by. You would be surprised what people will steal (even if they don't know what it is, if it looks like it might be worth some money ....).

  • Watch your weather as part of you planning process. Heavy cloud cover can really throw a monkey wrench in to your day.

  • He also told me these units don't like evergreen trees. Try to stay away from an area heavily forested with conifers if you can.

If you're shooting in a dense forest that is mostly coniferous, you'll need the backpack unit and antenna. His unit however, is about 3-years-old.

That said, this may no longer be an issue with the newer units (just telling you what he shared with me).

  • This one is important!! He said when you're going to be conducting field survey for multiple days, always try to pinpoint something permanent as a location for your base station.

If you're signal starts getting weak, it might be time to plant a rod somewhere (ex - at the top of a bedrock outcrop) or to find another survey monument to move to.

He stressed the importance of this one!! He said, "even if I have to come back 2 years from now, I can be rest assured that I have plenty of survey benchmarks to utilize if need be".

What this accomplishes, is that you have a "known" that is easy-to-locate/return to, that is nicely situated (reception, protected from theft), and relatively permanent. This school of thought ALSO shaves huge amounts time off of the set up process the next day, next week, a year later .....

  • Lastly, have an axe (if you're in remote/forested areas), lots of batteries, etc, etc. In short, be prepared.

I am envious!! That's a nice toy. Hope these suggestions are helpful, and have fun!!

share|improve this answer
1  
Thanks for the touch-up George. I wasn't aware I could add bullets, spacing, etc. I'm pretty new to the site. –  Dano Apr 14 '11 at 17:44
    
Welcome Dano. I just edited a bit for clarity and make it easier to read. –  George Apr 14 '11 at 17:59
    
Indeed!!! It looks & reads much better now. When I'm typing, none of my spacing, paragraph structure, etc takes hold. It just blobbs everything I've written into one big paragraph. I'm guessing that I haven't looked closely enough at the interface when I'm posting. I'll sort it all out in due time. Great site though!! Thanks for the welcome. –  Dano Apr 14 '11 at 18:15

Hi Nathan,

A few very important things dawned on me with regard to your question. My first answer (above) is an breakdown of the advisement I received from a respected surveyor. I do however, have a few tricks of my own to share with you, and I think you'll find find these suggestions invaluable (especially at the post data capture stage).

  • Prepare "before" you go in the field. Get any field maps, SR-Plans, etc scanned & printed out (if you have access to a plotter) and have your "targets" in mind before you head to the field (Iron Bars, Geodetic Benckmarks, etc). Poor preparation will cost you "hours" upon arrival. That, I learned the hard way!! Have copies that you can write on, identify things you wish to ground truth before heading out, etc, etc.
  • Do yourself and/or your GIS or AutoCAD technician a HUGE favor; make sensible descriptions of your data in the field.

Your data capture device will have a really user friendly interface. Put descriptions of what you're shooting in the appropriate columns. Populate the appropriate columns for labeling (ex - Test Pit 1-1, Monitoring Well 3-5).

If you spend a little extra time doing this, it will make for FAR less confusion back at the office. When you pull this data into CAD or ESRI, everything will already be in place allowing you to construct & add to your database. It only takes a few extra seconds to do this type of thing in the field. You might spend an extra half-hour out there today, but you can't imagine the time you'll save back at the office tomorrow.

  • Always bring a waterproof log book into the field

  • Capture your data in categories. Switching categories and creating new categories is very easy to do with this type of equipment.

  • If you're shooting the centre line of a road, work in a "CL_ROAD" category.

  • If you're capturing a simple elevation shot to build a DEM (Digital Elevation Model), switch your unit to shooting in an intuitively named category Like "DEM".

  • If you're shooting a sample point, switch to a category like "SAMPLE_ID" and take the time to identify the sample ID number in the "description" column.

You can name these categories anything that makes sense to you. Take that extra 10 seconds. It's worth it!! Once you get a bit of experience, you will see that the geodetic devices are quite easy to use in the ways I'm describing to you.

Trust me, when you get back to the office, you'll have a FAR easier time building a sensible GeoDatabase (or pulling it into CAD, whatever flavour you prefer). I have been handed some HORRIBLE survey data throughout my career. It's not fun revamping a poorly constructed database ..... trust me!!

Most of all ------- learn from every mistake. It will make you better at what you do!!

share|improve this answer

ProMark 500 Manual

Running Localization

Page 45 [PDF]

http://www.cropos.hr/files/documents/manuals/magellan_promark500_rm_a_en.pdf

Major Firmware upgrade for that model [FEB 2011] http://ashgps.wordpress.com/2011/02/13/the-promark-500-gets-a-major-upgrade/

New antenna NGS calibration http://www.ngs.noaa.gov/cgi-bin/query_cal_antennas.prl?Model=ASH&Antenna=ASH802129%20%20%20%20%20%20%20NONE

(Always have a fully charged new/spare battery.)

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.