How to Plan a 2D Photogrammetry Mission in GS RTK

2D Photogrammetry

1. To begin, power on your controller using the GS RTK app.

2. Connect to a WiFi network or hotspot to ensure base-maps will load to assist with mission planning.

3. From the GS RTK main menu, tap Plan in the bottom-left corner.

4. Tap 2D Photogrammetry.

5. Locate your site by panning around the map and using two fingers to adjust the zoom.

6. Drop a pin to start creating your survey area by tapping on the screen on the boundary of your site. 

7. Drop a minimum of three pins to produce a survey area. To move a pin, tap on it again to select it, then either use the wheel on the right or drag it around with your finger. You can delete the selected pin by tapping the trash icon or by double-tapping on the pin.

8. Display the mission settings by tapping on the white tab on the right side of the screen after completing your survey area.

The settings listed below with reasons are good guidelines to follow when planning 2D photogrammetry missions. 

Drone Setting	Set to	Question to Ask Yourself	Reason
Height	260-400ft (80-120m)	How high should I fly comparative to the takeoff point?	The height is a balance between how quickly you would like to complete your survey (higher makes it faster) and the ground sampling distance that you need. This range satisfies this balance.
Speed	Max Speed Allowable	How fast should I fly?	Unless you're trying to reach the required 10min mission time, increase the speed to minimize overall flight time. In low light conditions, reduce the speed and the shutter speed to ~640.
Shooting Mode	Distance Shooting	What metric is used to capture images?	Distance shooting allows the drone to capture images with consistent overlap.
Finish	Return to Home	What should I do after completing the mission?	Safety and not losing your drone. Once completed, the drone will make its way back to the home point automatically.
Altitude Optimization	Off	Is my terrain or altitude expected to vary during the flight?	A few oblique images are captured from the center of your survey area for optimization in certain software. By leaving this setting enabled, a survey will likely see accuracy issues and it will delay processing.
Relative Altitude (m)	0m	Is the terrain I want to survey at a different altitude to my home point?	Unless the terrain that you are surveying is at a much different height than your home point, leave this as 0m. On mines and quarries, consider changing the relative altitude.
Camera Setting	Set to	Question to Ask Yourself	Reason
Photo Ratio	3:2	How much of the image should I delete?	3:2 deletes nothing, utilizing the whole sensor. Everything else deletes data.
White Balance	Set to the conditions of the day	What conditions should I accommodate for?	Adjust the setting to reflect current weather conditions. Setting the white balance incorrectly will result in poor stitching and/or inaccurate coloring of your model.
Metering Mode	Average	How should the camera determine exposure?	Average metering uses light information from the entire image and creates an average for the final exposure. This type of metering does not weigh any part of the image. Sites with highly contrasting light and dark areas will benefit from an average metering mode.
Gimbal Angle	-90º	What should I point the camera at while flying?	All good surveys start with images facing directly down (nadir). These can then be complemented by angled shots (obliques). -90º is facing straight down, 0º is horizontal facing the direction of the drone.
Shutter Priority	Enabled ~1000	How should the exposure be controlled?	To avoid motion blur. Shutter priority tells the camera that a fixed shutter speed must be used. The camera can adjust the exposure with aperture and ISO. 1000 is usually a good place to start for sunny conditions. In low light conditions, reduce the shutter speed to ~800 and lower the speed.
Distortion Correction	Disabled	Should the distortion correction be applied by the camera?	Leaving the distortion correction off allows the photogrammetric software to undistort the images itself. The software usually does a better job. For any non-surveying purposes, leave this enabled.
Advanced Setting	Set to	Question to Ask Yourself	Reason
Horizontal and Vertical Overlapping Rate (%)	~75%	How much should each of the images overlap each other?	This provides enough overlap if some images are missing or of poor quality, while still building a contiguous model. The lower the detail on the surface below, the higher your overlap should be. If you have a large area to survey, you can look at reducing the horizontal overlap (no lower than 60%) to increase the area you can cover per battery.
Margin	Manual → 0	How much margin do you want to leave around the survey area?	Provided that you have covered the entire area you would like to survey accurately, you don't need any margin.

9. Tap Save and give your task a name.