Light Painting With Waypoints

Light painting is a photographic technique where a photographer uses a long exposure to capture the movement of a light source. The photographer can use a flashlight, LED lights, or even a drone to create patterns, write words, or draw images in the sky. By moving the light source during the exposure, the photographer can create unique and creative images that capture the essence of light and movement. Light painting can be done in a dark room or at night and can create stunning and surreal images that are not possible with other photographic techniques.

Light painting with a drone is a type of light painting where a drone equipped with LED lights is flown in the air to create patterns and designs. The drone's movements and lights are captured using a long exposure, resulting in stunning and unique images.

This is a step-by-step guide to light painting with a drone. There are a number of steps to complete and some of them are manual. The steps include the use of several software components:

Google Search (to find a suitable drawing)
Google Earth Pro (to create the initial path)
Litchi's Mission Hub (to import and make height adjustments)
Litchi Mission Rotator (to rotate the path around the X-axis (Longitude-axis)
Virtual Litchi Mission (to confirm and validate the flight)
Fly the mission using either Litchi or DJI Fly using a DJI drone that supports waypoints

Light painting with a drone requires some skill and experience in flying drones and using long exposure photography techniques. However, the results can be incredibly rewarding, and the possibilities for creativity are endless.

Step 1: Obtain an image representing the shape to be painted.

Although any image will work, a line drawing would be most suitable for this step. When searching, using the term "drawing" helps to narrow down the search results to only include appropriate images. For example, this sample image was found using the search string "roadrunner drawing". Save the image to your computer.

If you are able to find an SVG file of the object to be painted, there is a converter that will directly convert an SVG file into a Litchi waypoint mission. This will eliminate the manual work of drawing a path around the object. If an SVG file is available, convert it, and go directly to "Step 4" below.

Image displayed as an Image Overlay in GEP

Step 2: Import the image as an "Image Overlay" in Google Earth Pro

The image to be traced needs to be imported as an "Image Overlay" in Google Earth Pro. Once the following steps have been completed, you should have the image overlayed similar to what is shown on the right.

Navigate to the desired flight location in Google Earth Pro.
Select "Add Image Overlay" from the toolbar at the top of Google Earth Pro.
Browse to the image downloaded in step 1.
Set the transparency slider to an appropriate value.
Use the image overlay controls to adjust the image to the proper size and location. Since the image will be rotated around the X-axis (Longitude-axis) make sure the Google Earth view is oriented with "North" pointing up. Size the image so that when rotated up, the flight path will not exceed flight limitations in your country (usually 400 ft or 120 meters).
- NOTE: It is recommended to size your image in conjunction with using the "Ruler" tool. The height of the image will correspond to the height the drone will need to fly.
Select "OK".

Image with path drawn around the perimeter

Step 3: Create a path around the outline of the image

At this point you will need to open the "Add Path" tool and manually draw an outline around the subject matter in the image. You may start the path anywhere you want. Keep in mind that the starting point is where the drone will begin the mission once the path is rotated vertically.

There are ways to modify, append, insert, and delete points in the path. The way in which these are done is beyond the scope of this tutorial. Also, while it is possible to click and drag a path, it is recommented to place every point by clicking instead. The dragging method produces too many points that will be too close together.

Tip: It may be desirable to temporarily uncheck the "Terrain" checkbox in the "Layers" section on the left while drawing a path around the image.

Step 4: Remove waypoints that are too close together

Paths drawn in Google Earth Pro will likely result in a few waypoints that are closer together than what Litchi allows. Those extra waypoints need to be removed using the Remove Close Waypoints utility.

Specify the kml/kmz file containing the path.
Remove the close waypoints.
Save the output as a CSV file.

Tip: It may be desireable to note which waypoints are too close and manually adjust them in Google Earth Pro instead of having the utility remove those points automatically.

Step 5: Rotate this mission using the Litchi Mission Rotator

Use the Litchi Mission Rotator to rotate the mission contained in a CSV, KML, or KMZ file around the X-axis (Longitude-axis). Save the result in a Litchi CSV file.

Import the rotated mission into Litchi. This new mission will initially look like all waypoints are in a straight horizontal line. That is to be expected because the entire flight has been rotated into the X-Z plane. Use Litchi's "Rotate", "Translate", and "Scale" functions to orient the mission into its final, desired location.

Rotate: Select "Rotate" tool. Click anywhere off the mission to define the center of rotation. Click on and drag any waypoint to rotate the entire mission. Unselect the "Rotate" tool.
Translate: Select the "Move" tool. Click and drag any waypoint to move the entire mission. Unselect the "Move" tool.
Scale: Click on any waypoint and drag left or right to scale the mission around the selected waypoint. Unselect the "Scale" tool. Note that the scale tool only scales in the longitude/latitude directions without affecting the height. Use of this tool will distort your light painting.

The Litchi Mission Rotator will add one or two POIs to your mission.

POI #1 will be added below (to the south) of the rotated mission. After using Litchi to move the rotated mission to its final location, POI #1 should be positioned to the location of the land camera. This will cause the drone's heading (and light) to always point at your camera.
A second POI (POI #2) may be added above (to the north) of your mission. This POI is only added if you have specified any waypoints where the drone is to be turned away from your camera. After moving the rotated mission to its final location, POI #2 should be positioned behind the mission and away from the land camera causing the drone to point away from the land camera for any turned waypoints.

Rotated mission displayed in Google Earth Pro

Step 6: Confirm rotated mission in Google Earth Pro

If the mission is exported from Litchi using Virtual Litchi Mission, you will see the original image overlay with the newly rotated mission displayed above it. By default, Google Earth Pro will extend the path to the ground. If you wish to see only the rotated outline as shown to the right, right-click on "Smooth Flight Path" in the left menu of Google Earth Pro. Select "Properties". Select the "Altitude" tab. Uncheck the "Extend path to ground" checkbox. Once done, only the outline is displayed.

Light painting mission simulated in Google Earth Pro

Step 7: Simulate the light-painting mission in Google Earth Pro (optional)

I have written software that takes a multi-line path stored in a KML file and converts it to a series of line segments placed end-to-end. The software adds Google Earth extensions to the KML file that allows one to animate the path in Google Earth Pro. This video shows that path animation. This step is not necessary but is an interesting addition to this light-painting process.

This step is a bit complicated. If you need help with this step, contact me. I can help to create a suitable viewing mission to produce similar results for you.

Step 8: Fly and record the mission

At this point your vertical mission is ready to be flown and recorded. For light painting you will probably want to attach a strobe or light to your drone. You will also want to have a camera on a tripod to capture the flight. Details on how to do these steps are up to you.

Tip: It is also possible to fly these light painting missions using a DJI Fly drone (Mavic 3, Mini 4, Air 3) by converting the light painting mission CSV file into a KMZ file using the "Litchi to DJI Fly" converter utility.

More Information on Light Painting

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