How to Plan a 3D Photogrammetry Mission in GS RTK: Multi-oriented


3D missions differ from 2D missions regarding data capture and upload. This article will explain how to plan a 3D mission.

If you wish to use the Vertical Face Imagery option please ensure you have turned on the option to produce Vertical Face Imagery when configuring the outputs in the Uploader. The Vertical Face Imagery option is not required to be able to process 3D missions, just to create the VFI output.

If you have any questions, your CSE can help you with best practices and processing times with you.

To view vertical face imagery, turn it on in the Survey Explorer

While the Propeller Platform works best with 2D photogrammetry missions, in certain cases, a 3D photogrammetry mission produces more actionable results. 

3D multi-oriented missions involve a single flight directly overhead of the site with the camera facing straight down (nadir). This is followed by four flight paths with images captured at different camera angles (oblique) for five segments. The oblique segments are optional and can be toggled on or off depending on the mission's requirements.

This mission type should only be used in specific circumstances, namely when you are flying in a mine or quarry, and you need more detail and accuracy on the vertical faces. Please work with your Customer Success Engineer to determine the best mission type for your site

For example, if you need an accurate model of a bench for blasting planning, this mission type can provide a more accurate point cloud than a laser scan of the vertical face, allowing for safer blasting. 

Use the steps below to plan a 3D multi-oriented mission 

1. Tap 3D Photogrammetry (Multi-oriented).

2. Locate your site by panning around the map. Use two fingers to adjust the zoom.

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

4. Drop a minimum of three pins to produce a survey area. To move a pin, tap it again and either use the wheel on the right or drag the pin with your finger. Delete a selected pin by double-tapping it or tapping the trash icon.

Before you can change the mission settings, you must mark your survey boundaries. 

5. Display the mission settings by tapping the white tab on the right side of the screen.

GS RTK Settings Tab.png

Important You can change the settings for individual mission segments by tapping on the circled numbers. 

In the first screenshot below, section 1 is selected and appears white. The other segments are gray. Section 5 (one of the oblique flights) is selected in the second screenshot. 

GS RTK Multi Oriented Segment 1.png

GS RTK Multi Oriented Segment 5.png

The settings listed below are a good guideline for planning 3D multi-oriented 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 (lower makes it better). This range satisfies this balance.
Speed Max Speed Allowable How fast should I fly? Unless you're trying to reach 10min flight time (required), increase the speed to minimize overall flight time. In low light conditions, reduce the speed and the shutter speed to ~640.
Oblique Altitude 260-400ft (80-120m) How high should I fly comparative to the takeoff point? You can set the height of the oblique flights differently than the nadir flight. Just note that the ground sample distance (GSD) will be different.
Oblique Speed Max Speed Allowable How fast should I fly? Unless you're trying to reach 10min flight time (required), 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.
Relative Height Varies Is the altitude of my flight area different than the altitude of my take-off point? You can set the relative height for individual segments of the mission. This would allow for vertical offsets for different sections of the mission depending on your needs.
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 accomodate 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 weight any part of the image. Sites with highly contrasting light and dark areas will benefit from an average metering mode.
Oblique Gimbal Angle -60º What should I point the camera at while flying? The first flight will be nadir (gimbal at -90 or straight down). You can only set the gimbal angle for the oblique flights.
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 apeture 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 nonsurveying 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 for if some images are missing or 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 survery, you can look at reducing the horizontal overlap (no lower than 60%) to increase the area you can cover per battery.
Oblique Side and Oblique Frontal Overlapping Rate (%) ~75% How much should each of the images overlap each other? This provides enough overlap for if some images are missing or 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 survery, 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.

6. Tap Save and give your task a name.


I still can't do it!

We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.

If you're stuck, the Propeller hardware support team may be able to help. You can contact them by emailing hardwaresupport@propelleraero.com.au.

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