Topography
Topography
(OP)
First off, I am a Civil guy w/minimal survey field experience, so please excuse any mis use of terminology. My question is, can anyone recommend a type of instrument(total station?) that will aid in obtaining and plotting topography over relatively small tracts (less than 10 acres). This will be used to field check existing grades prior to construction. Does plotting this information require a large learning curve? Any info is appreciated.





RE: Topography
1) Give your surveyor a digital copy of your site (existing conditions), and have them import their surveyed data points into your drawing. They can also generate contours for you if required.
2) If you have a suitable Civil Eng. software suite that works within AutoCad or Microstation (programs like EaglePoint and Land Development Desktop come to mind), you can import a "points file" into your drawing. A points file is typically and ASCII-text file that contains information about each surveyed point (Pt. #, Northing, Easting, Elevation, Description, etc..). The software will let you produce contours and do other
Learning to do the basic imporation of data points is not that difficult to learn, but the price of some of the software may be prohibitive if that is the only thing it will be used for.
RE: Topography
Accuracies are probably comparable to traditional theodolite techniques, but DGPS offers the possibility of getting direct digital terrain data more quickly and already in a processed state. A person with a portable computer or radio link could simply walk the terrain and record the terrain elevation data in real time. Since GPS updates at a 1 Hz rate, thousands of data points could be acquired in relatively short order. A 10 acre plot could be covered with a small tractor or ATV and you'd simply stop every 10 ft or so and get a reading directly recorded. The only post processing would be to re-grid the data for contour plots and so forth.
Traditional survey would require some setup at specific spots and post processing of the data to get the terrain elevation data. Re-gridding would also be necessary.
TTFN
RE: Topography
TIMOTHY DAY
SURVEY MANAGER
ARCHER WESTERN CONST.
RE: Topography
RE: Topography
KRS Services
www.krs-services.com
RE: Topography
Your surveyor should be able to quickly plot the information gathered. I usually request, as a component of a project, a preliminary topographical plan be developed. I alsways want to have all highpoints, breakpoints, lowpoints, accesses, structures, tree lines, utilities, property lines and monuments, unusual features and observed drainage courses plotted. From there, it is transferred to Autocad and expanded upon. Best of all, it is very inexpensive and worthwhile considering the cost to have me stumble about for weeks on site and then have to undertake plotting the info!
For me, I find it better to contract that work out to those who have chosen surveying as a lifelong profession.
KRS Services
www.krs-services.com
RE: Topography
Thanks again for the input.
RE: Topography
RE: Topography
KRS Services
www.krs-services.com
RE: Topography
Total stations are usually adequate for most site work and have the added advantage to be able to measure under cover etc which GPS does not - Beware of Multipath errors on GPS.
If you do drive around a site with GPS (which is great) be aware that the vehicle could bounce and thus give you erroneous height readings - It all depends on the accuracy you need. Most Total stations (such as Leica) give a points file compatible format with GPS usually readable directly into packages such as Autocad - That is in principle - in practice it does involve some learning of procedures etc.
You can also now use things such as A laser CYRAX - or as a very good replacement for the stadia an automatic level (on flat sites) but I feel that if you do that might as well have a total station which will allow for steep sites etc.
Good luck with your project.
RE: Topography
By the way, my little hand held GPS, a Garmin GPS-12, is accurate to +/- 15' or so, if I use the average function of the available satallites, not survey quality. I too would like to know about one of those 100 mm ones, they can't be in the $200 range <G>
RE: Topography
Regarding the bouncing. We take readings when stopped. It's firmly anchored to the rack on the quad, so the elevation stays constant. Works like a charm for large topographical areas.
KRS Services
www.krs-services.com
RE: Topography
http://www.fondriest.com/products/trimble_ms750.htm
as well as:
http://www.cmcelectronics.ca/products-services/custom-elect/rtstar-GPS.html
TTFN
RE: Topography
KRS Services
www.krs-services.com
RE: Topography