Capture Guide – Pro-tips to a better capture
Did you know that too much or too little overlap can cause a model to fail digital reconstruction?
Often in the processing phase, we reduce the number of images used, as this can provide optimal 3D models. If your unsure urge slightly on the higher side. (80/80)
Recommended Overlap: 75/75
One of the most significant issues we encounter is a lack of transitional imagery which leads to incomplete or fragmented corners or tower structures.
- Aim for a minimum of one image per 30 degrees when transitioning around corners or;
- For structures like towers, consider capturing orbital imagery every 10 degrees.
Recommended Transition: 30 Degrees
PRO TIP: For intricate or detail-heavy assets, consider increasing the number of transition shots
When targeting a specific resolution or Ground Sample Distance (GSD), ensure accuracy when calculating the
offset distance and adhere to it, closely. The camera and lens combination will determine your offset distance.
Unfocused images reduce the quality of your model, frequently occurring for entire flight lines. There are several methods of setting focus.
We recommend the following options:
- Try using “AF Assistant” before a mission if using a DJI drone,
- Manually set the focus on the ground using your offset distance. Focus your drone on an object (a wall or similar) and once set, switch to manual focus.
- For non-DJI drones try using Hyperfocal distance for setting focus. (Don’t forget that aperture will affect the distance).
PRO TIP: Always check that your images are in focus before leaving the site.
Manual VS Auto Flight
Where possible, conduct flights in an automatic mode to achieve a consistent offset distance. For towers, we recommend semiautomatic orbits with manual yaw inputs to keep your the subject centred within the frame.
Where to have the Horizon?
We recommend omitting the horizon whenever possible. Capturing imagery looking down (below the horizon) and imagery looking up (above the horizon) is ok. This is more evident when you can “see-through” an asset, such as a telecommunications tower.
There are several items to consider when selecting a flight speed:
- It is essential to minimise “Motion Blur”. We recommend less than half a pixel,
- Consider the cameras ability to achieve continuous shots. How often can your camera trigger a photo continuously?,
- Know your camera settings. We recommend using aperture priority mode, an ISO not above 800 (before the image becomes noisy) and the fastest shutter speed you can achieve.
PRO TIP: Normally, a lens is sharpest between and aperture of f 5.6 and f 11
For consistent positioning data, we recommend PPK/RTK capable drones that automatically log image position. For non-PPK/RTK drones, you may opt to hot-swap batteries (if able) to minimise GPS errors induced when power cycling.
Files names should not be duplicated (DJI restart numbering after 1000), have spaces or special characters. If you are NOT using PPK/RTK or hot-swapping batteries, after each battery swap, we recommend capturing a photo from a common take-off position and naming each file to reflect it.. (e.g., DJI_0001-ground-shot1) which will enable us to calibrate the Z-axis when modelling.
The ideal lighting conditions typically occur on an overcast day resulting in minimal shadows.
We recommend auto exposure in aperture priority mode to keep the asset consistently light. However, we have found that using centre-weighted metering to be the most effective. Unlike standard exposure settings; centre weight attempts to give you a correct exposure for the centre of the frame.
PRO TIP: Don’t worry when the sky is overexposed, It is a good thing when modelling.
For consistency do not use automatic white balance (WB), This can lead to each photo being a different tint. Select a manual White Balance to suit the lighting conditions.
Do you have a tip?
We would love to hear how we can make this guide better. If you have any suggestions please get in contact with us at [email protected]