Field Checking Your Courses
You must field check your proposed courses and control locations.
Your courses should be designed around interesting routes between controls, not by control locations alone. Therefore, it is important for you to walk as many of your routes as possible to make sure they are well-mapped and as enjoyable as you hoped.
You will find some of the locations you choose will not work well due to mapping problems, vegetation problems, etc. This is the chance to scout a new location and mark it on your field map. You can flag control locations with survey tape marked with the course and control number, or, if it won’t be out too long (less than a week), and there’s little chance it will be stolen, you can hang the actual control, being careful to record its code. Please remove and properly dispose of the survey tape when you hang the control.
Attack each control location from multiple directions to confirm the chosen feature. If there is any doubt, move control to a location where there is no doubt. As you check, you may find more interesting or appealing features in the same area
Checking Control Placements by Smartphone
You can use a smart phone with a GPS and an export of your OCAD course map to help verify locations of your controls. Details are in this post from May 2018.
Please be aware that 1) not all our maps are accurately referenced to GPS coordinates, 2) and all GPS devices have some amount of error, especially under dense tree cover. Please use common sense and do not implicitly trust the GPS.
If you think you have found errors with the map, please report them to the VP of Mapping. If you can do this early enough, the VP of Mapping may be able to make corrections in time for your meet. If not, do not use this location for a control.
Checking Control Placements by GPS
- First draw your courses using OCAD. When you go out to place controls, carry a GPS a create waypoints at each of the control locations (WGS 84 datum).
- OCAD can import waypoints and tracklogs directly from a Garmin GPS. If you have a different brand of GPS you will need to extract the information from the GPS and save in .GPX format to load into OCAD.
In OCAD, set the coordinate system for the map using the “Options->Scales…” menu option. Choose “Real World Coordinates” and enter the values for the map that you are using from the following table:
- Click the “Change…” button for the coordinate system and set the inputs to UTM, Zone 6 North.
- Click “OK” to close the two dialogs boxes.
- Choose the “GPS->Import from GPS…” menu option. If your GPS is connected to your computer and turned on, the status should display “GPS Connected”. If the status shows “Unable to connect to GPS”, you may need to click the “Settings…” button to set the correct communications port and speed.
- Once the connection to the GPS is established, click the “Get Waypoints” button to import the waypoints from the GPS. Or, if you have already saved the waypoints to a .GPX file, click the “Load…” button and load the file.
- A list of the loaded waypoints should display in the left part of the form. Select (by clicking on) the waypoints that you want to use. If you want the waypoint name to show on the map, click the checkbox for “Set Labels”. Click the “Create” button to add the selected points to the map. It doesn’t look like anything as happened, but they should appear when you close the dialog box.
- Close the dialog box, then zoom the map to an area where one of the waypoints should be. You should see a small light-grey “+” at the waypoint location. If you created labels with the “Set Labels” option, there should also be some text for the waypoint name.
- You can change the symbol for the waypoints and/or the labels. Select one of them, then select the symbol that you want to use (from the symbol list on the upper right side of the screen). Click the “Change all Symbols” button from the toolbar at the top of the screen. The button looks like
- Look at each of the waypoints and controls to verify that they agree. They probably won’t match exactly due to lack of accuracy of the GPS and errors in our mapping, but they should be close. If you find that the waypoint shows up on a different feature from your control, you should probably go back out to re-check and fix the location. If you find that the waypoint is a significant distance from the control, but doesn’t appear to be on a different feature, it may be an indication that the map is inaccurate in that area and that perhaps it should be fixed or you should use a different control location. Once you are done checking the locations, delete or hide all the GPS points and labels so that they don’t print on the course maps.