In one of the previous exercises (4) each group conducted a survey of a portion of campus using a distance and azimuth survey method. This method of surveying is good for on the spot or cheaper surveying, but a total station is a much better tool for more accurate readings. Another perk of the total station is the fact that it gies a z value, or elevation data. The aim of this exercise is to utilize the total station's equipment to survey the campus mall. The campus mall is around a hectare in area. The survey was done from east to west and then from north to south. The topography of the region shows an area of a small hill starting in the northeast corner and rolling to the opposite. The image in the results section of this post shows the final product.
Study Area:
Each group set up the total station in the same general area. There was an orange circle spray painted into the grass on the mall where we were meant to survey. The campus mall is located in a central area between the following locations: McIntyre Library, Davies Center, Phillips, Schneider, and Schofield. The goal of this project was to obtain surface data using the total station. The field that was survey contains large slabs of granite blocks for seating, an outdoor amphitheater, Little Niagara river, and the green space.
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| Image1: The image above shows our field methods class on the campus mall learning how to use the Topcon total station. Professor Joe Hupy can be seen in the orange jacket and our GISP, Martin Goettl, in the green polo. Here Professor Hupy |
In order to gain an accurate total station reading there are many steps that must be followed. This process all begins with setting up the tripod. The tripod is essential for getting a level base reading. It is paramount that the tripod has a wide base with equal spaces between each of its three legs. Each leg should also be firmly planted into the ground to give further support. If you must survey on an uneven surface then the tripod's legs can actually be adjusted in length. If the tripod moves at all during the survey then there is a potential for every point after that to be inaccurate.
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| Image 2: Here is an image of Blake Johnson and April Leistikow setting up the total station. The tripod is set up with a wide base of support and each leg is firmly pressed into the ground. As you can see, the total station is also put onto the tripod at this time. |
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| Image 3: The above image shows Blake Johnson adjusting the total station so that it is level. The black knobs at the base of the device, which is at the bottom of the photo, are used to level it out.The total station is nearly ready to be booted up for data collection. |
Data Collection:
The information below was provided by Professor Hupy to help guide us in our efforts to set up the total station by ourselves. In order to best relay the way in which we were able to make the total station work the directions for the assignment are presented here.
1. Set up Blue Tooth
a) Turn on the total station (TSS)
b) Turn on the station Bluetooth. This is done within the menu area, and within the parameters portion.
c) At this point, you will not see a Bluetooth symbol appear on the TSS. This will appear after you set up the TopSurv Job.
2. Set up TopSurv Job
a) Set up TopSurv: Open up TopSurv (if no short cut appears find the EXE in the Flash Disk by clicking on My Device from the home screen, then flash disk, and then TTS folder)
b) If TopSurv has icons instead of menus click the Topcon Icon in the upper left corner and Switch Menus
c) Inside TTS - Make a new job
i. The open job menu will appear
ii. To make a new job click new
iii. To type in a name click on the space and a keypad will open up
iv. Click next choose My RT DGPS for GPS + Config and My Reflector less for TS config.
v. Set the projection accordingly. If you are planning to enter the coordinates in manually from a different GPS unit you need to choose the same projection as the coordinates that you have from the other unit.
vi. You may also need to change the datum (ex if you are using UTM Zone 15N NAD 83).
vii. Do NOT check grid to ground
viii. Set the Geoid to the first one that is in the list. Click next
ix. In the units menu set your distance units to meters and choose whatever else you want for temp etc.
x. Coordinate type will be Grid, coordinate order should be Easting, Northing, Elevation Height and leave the rest.
xi. Turn on alarms if you wish.
xii. Finish
d) The blue tooth manager will appear. Select the GPT (TSS) then choose select. It should connect to the GPT. The blue tooth light on the GMS-2 should be blue indicating that it is connected.
e) You may need to go to the Job Menu, and go to Observation mode. Select Total Station. You could select GPS if you were using the GPS+ a LAZER.
f) If a window pops up asking you for codes. Type in the following codes for
1. The key value should read 2951612344
2. TS: 142601006
3. GIS: 142601214
3. Collect GPS points with the GMS2 in TopSurv*
a) From the Job menu, go to Obs mode
i. Check GPS+
b) Then go to collect menu, and collect features
c) The point will auto label OCC1 – keep tract of this as you will need the name again
d) Place the GMS2-s over the laser point for the OCC. and click start. The GMS2 will begin logging points.
e) If the GMS-2 will not log points, click on the settings button and the top and choose solution type DGPS, Auto. You can also set the number of positions to be averaged. This can also be set from the job configuration menu.
f) Once you have collected enough points for a position for the OCC you can click accept.
If you wish to also record the location of the Back Sight at this time you can follow the same procedure.
4. To begin the OCC/BS setup
a) Go back to the job menu, observation mode, and choose Total Station. Then proceed with Step 8 (skip step 7)
5. If you have X, Y coordinates from a different GPS unit and you wish to add the OCC/BS points in manually then:
a) From the edit menu go to points.
b) Click on Add
c) Then click on New
d) Name your point accordingly (ex. OCC1). Type in the coordinates you obtained from the GPS unit. These MUST be in the same coordinate system AND Datum as the settings from the GPS unit.
e) Click finish.
f) Repeat for the BS
6. Set the Occupy Point (OCC) and Back Sight (BS).
a) Go to the Col menu, choose OCC/BS setup
b) If OCC/BS does not appear in the menu check the File menu, Observation Mode and be sure it is set to Total Station.
c) In the BS setup tab, in OCC spot click, on the drop down menu to the far right and choose from list the point for the OCC (either that you collected with the GMS2 step 6 or added manually step
d) Choose the point where the TSS is located – the OCC point you entered in the previous steps
e) Then set the height of the instrument by measuring the to the mark on the TSS from the ground up
f) Then set the height of the prism from the rod
g) If you wish to enter the BS point from the list
i. Then be sure the button next to the pointing figure says BS Point, if it says BS Azimuth click the button and it will change to BS point.
h) Use the pull down menu to find the BS GPS point (same way you did with OCC). Select that point.
i) Then sight the TSS to the BS. You do not need the prism on the BS you just need to have the TSS sighted in the exact direction of the BS.
i. FYI if you want to put the prism on the BS – no harm will be done
ii. FYI if measure dist to BS is checked then the prism must be at the BS and the TSS will shoot the BS.
j) Once the TSS is sighted to the direction of the BS then click HC set. The BS Azimuth will then be set to zero even though it is not north. This is OK because the software/TSS automatically does the calculations. This is so everything is relative to the angle between those two points.
k) If you wish to use BS Azimuth
i. Orient the total station in the EXACT direction of the BS and enter in the angle from north for the BS. You can use a compass or laser find to measure this angle. The follow step j above.
7. Collect Data
a) Go to the Col menu and choose observations.
b) Then click measure once the TSS is sighted to the prism. Continue to do this and make sure that the point’s id numbers are increasing.
c) If you wish to verify the data, go to edit and list and look at the points you collected. You can also view these points on the map tab
d) Continue collecting data.
e) Be sure that if you change the height of the rod you must enter the new height of the rod into the collection screen for each point.
8. To move Total Station
a) If you need to move the TSS then you will need to move it to the BS and go back to step 6 (setting the OCC and BS) and change the OCC to the BS and set a new BS
9. Exported collected points to a shapefile from TopSurv
a) Go to the job menu, export, to file
b) Choose points
c) If you export as Shapefile format (this will only be the points, not E, N, Z)
d) If you wish to have a file with E, N, Z and any codes or comments choose Topcon TXT file.
e) You will need to open the text file and eliminate the Header Info and the extra breaks. Delete the highlighted info from the example.
f) Transfer the file to your computer using Active Sync. Make sure you export this information to your user folder, and make sure the information reflects your group name.
Results:
Once all of the points were imported to the computer they were transferred to an .mxd file for further interpolation. As can be seen in the image below, a surface model was created to show the z (elevation) value. Our group utilized the Kriging method of interpolation to show the elevation of the campus mall. The color scheme emphasizes higher elevation with reds and lower elevation with blues.
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| Image 4: The image above shows the spatial interpolation method known as Kriging. The red areas represent regions of higher elevation which blow represents areas of lower. Each point on the map represents a region where data was collected for the total station. |
Discussion:
The goal of this exercise was to learn how to use the Topcon total station. During the survey our group traded jobs so that every person could get a chance to use each tool. Prior to actually starting the survey our group talked about how many meters that we wanted each point to be apart from one another. We came to the consensus that 10 meters would be the best option because it wouldn't take too long and yet still gave us a good idea of the topography.
Some problems were addressed during our survey and finally data importation. The first anomaly that was encountered was that the device turned itself off, but when we turned it back on it still allowed us to continue with the survey without any foreseeable problems. Many groups encountered the issue of losing the blutooth connection, however we never encountered that issue. Finally, when we tried to import our data onto the computer as a text file it said that there was only one point available even though the device plainly said that there were over 100. With the help of GISP Martin Goettl we were able to overcome this issue and plot the points for interpreation and symbolization.
Conclusion:
When all was said and done this project was a blast! It was a headache to get our data uploaded, but the process of taking the points was actually fun. By taking turns with each tool and teaching each other how to use each part we were able to gain a better understanding of how to perform a survey properly. If time permitted, a better survey could have been done which would have made more variation on the Kriging interpolation method. Our group ran like a well oiled machine during the activity even though it was tough to get everyone together for the actual survey.
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