Light Painting With Litchi

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:

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.

Sample of image to be painted

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.

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.

  1. Navigate to the desired flight location in Google Earth Pro.
  2. Select "Add Image Overlay" from the toolbar at the top of Google Earth Pro.
  3. Browse to the image downloaded in step 1.
  4. Set the transparency slider to an appropriate value.
  5. 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 conjuction with using the "Ruler" tool. The height of the image will correspond to the height the drone will fly.
  6. 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.

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

Outline displayed as a Litchi Mission

Step 4: Import this path into Litchi

Once the path has been completely drawn in Google Earth Pro, you will need to save it as a KML file.

  1. Location the path in the menu on the left of Google Earth Pro. The name will be "Untitled Path" unless you changed the default name with creating it.
  2. Right-click on the name and choose "Save Place As...".
  3. Change the "Save as type:" setting to "KML".
  4. Save it with the name of your choice.

NOTE: I could have created the Litchi Mission Rotator" to work directly with KML files. I chose to make it import Litchi CSV files to that it could be use to rotate any Litchi mission and not only KML paths.

A rotated mission displayed in Litchi

Step 5: Rotate this mission using the Litchi Mission Rotator

Import the KML file saved from Google Earth Pro into Litchi. Review the shape of the mission. Export this mession as a CSV file.

Use the Litchi Mission Rotator to rotate the mission contained in this CSV file around the X-axis (Longitude-axis). Save the result in another 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.

It may also be a good idea to right-click to position a POI marker at what will be the take-off/home location. Then use the "Select All" function (Select one waypoint. Control-select a second waypoint. Select All) to set that POI (POI #1) and make sure "Focus POI" is selected. This way, if the drone has a light facing forward, it will always point at the home location where the camera will capture the light painting.

Rotated mission displayed in Google Earth Pro

Step 6: Rotated mission confirmed 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 on the right, right-click on "Smooth Flight Path" in the left menu. 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 6a: Simulate the light-painting mission in Google Earth Pro

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.

Step 7: Fly and record the mission

At this point your vertical mission is ready to be flown and recorded. For light painting you may 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.

More Information on Light Painting

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