This article/blog is a continuation of my coverage into the Leica BLK3D and it being more than your typical disto laser-measuring tool. Before diving into details and directions on how to use the BLK3D from Leica Geosystems though, we need to explain some of the terminology first.

Reality Capture: The process of photo capture itself by using the BLK3D.

Single-Shot: Capture of a single stereo photo to obtain measurements from.

Multi-Shot: Capture of multiple stereo photos of the same scene from slightly different positions to get the most accurate measurements from.

Baseline: Maximum distance between the cameras during Reality Capture. This distance can be increased by using multi-shot from slightly different positions.

Considerations: Achieving the Most Accuracy Out of the BLK3D

In order to get the best results from the imager, it is important to know several factors that can influence the accuracy of measurements:

Angle of Intersection

Both cameras take pictures of the same object, just from different positions. The intersection angle is given by the two lines of sight from the two cameras.

The picture above shows that accuracy is better if the angle “a” intersection is bigger. The angle “a” is affected by distance to the object “D.”

Baseline length “B” (distance between cameras) – A bigger angle of intersection “a” equals better results.

Ultimately, a photo taken from a shorter distance will increase the overall accuracy.

Single Shot VS Multi-Shot

For photos of objects at a closer range, one single image can provide you enough data for linear and area measurements. As the range of your shot increases, more images become necessary.

You are prompted to take up to two multiple shots from slightly different positions to increase the length of the baseline. The object you are measuring must be visible in all pictures.

Measuring an object from “edge to edge” can result in a reduced accuracy. You would want to back away from the object and make sure to position the target so that it is in the middle 50% of the photo.

Key Points to Remember

• Capture and measure with multi-shot images. Make sure to use a baseline of 10% the distance from the target to get the best results,

• Ensure your BLK3D is stable and has proper lighting. Use LED lamps or the integrated flash to enhance lighting when needed.

• In case of larger areas to measure, break them down to smaller areas.

• Remember to capture the target in the middle 50% of the screen.

For more information on Reality Capture, please visit our Reality Capture Page.

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This blog is written by Reality Capture Specialist Josh Hunter. If you have any questions or need help with your Reality Capture needs, please email us at whyATG@atgusa.com or reach out to us on LinkedIn.