Adding Control Points and Imagery (6:40 min)

Adding Control Points and Imagery – Practice Exercise

Task 1: Import the GPS land survey control points

Open the practice file, Base Map.dwg.
On the settings tab of the Tool Space right click on the drawing name at the top and select Edit Drawing Settings.
Select the Units and Zone Tab and verify the settings to match the image below. Note this drawing is using meters and the coordinate zone code is CO83-C.

Click OK to dismiss the Drawing Settings dialog box.
On the Insert tab go to the Import group and select Points from File.
On the Import Points dialog select the “plus” icon.
Browse to the PNTs folder of the dataset. You may need to change the files of type to CSV.
Open GPS Control Points.csv file.
In the dialog box scroll to the bottom of the Specify point file format and select PNEZD comma delimited.
The preview window will parse the first few lines of the file so that you can validate that you have chosen the correct format.
Check on the box to Add Points to Point Group.
Select the Create Group icon.
Create a new group named “GPS CONTROL”. Select OK to dismiss this dialog.
Verify that there are no checked boxes in any of the Advanced options.
Select OK to dismiss this dialog and to start the point import.

Task 2: Validate the Location of the Control Points

On the Prospector tab expand the point group collection by picking on the plus sign.
Right click on Points Group and select Update to sync the new data.
Next do a quick test to see that the No-Display group is working. In the point group properties move the No Display group to the top of the stack and see that the points are now not seen in the drawing canvas. Return the GSP Control group back to the top of the stack so the points are displayed.

Change the scale of the view to 1:5000 so the COGO point markers and the labels become bigger and easier to see.
To see if these GPS points are in the correct location select the Geolocation tab on the ribbon and turn on the Hybrid map so we can see a mix of aerial images and map features. Note the control points do appear in the area of our project.

Task 3: Use Map Tools to Add the Ortho Photo

This opens the Data Connect panel and you can see all the different geo-spatial data types that we can use.
Select Add Raster Image or Surface Connection.
You now have the choice to select a single image file or connect to a folder that might contain many image files. Select the single file option.
Browse to the Images folder of the course dataset, and open the Orthoimage.tif file.
Looking closely at the coordinate system information we see that the image file has a different system than that of the drawing. These two systems can transform so the image will be located correctly in our Base Map drawing.
Click on Add to Map and the image is connected. This may take a few moments.

Task 4: Validate the Ortho Image with the GPS Control Points

Check for accuracy by zooming in on one of the control points. You may want to change the scale to 1:500 to get a smaller COGO marker and label.
Resample the raster data by clicking on the Orthoimage feature in the Display Manager of the Task Pane. In some instances, you may see the image become sharper in focus.

Verify that the GPS control matches to the center of the white panel points in the ortho image.
To restore the entire image select Zoom to Extents.

Task 5: Compare the Ortho Image with the Bing Maps Imagery

On the Geolocation tab turn on the Aerial Map.
Zoom in closely to the east edge of the orthophoto at Mineral Ave. Notice the misalignment. This is expected and is because the drone captured image is much more accurately positioned to the real surface. We can use the Bing imagery for approximations and we will use the drone orthoimage for accurate details.

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