Making Reality Capture Point Colours More “Real”

Realistic colours in point clouds improve perception that can foster better analysis and decision-making.

Point clouds from laser scanning systems that incorporate RGB cameras can be colourised when post-processed or, in some cases, on the fly. However, the varied lighting conditions that can occur within a single project as the user moves between indoor and outdoor spaces or from shadowed corners to the glare of bright lights can result in colours that, while accurate, do not capture the colour experienced by the human eye on site. Many practitioners view this as “something we have to live with.” Fortunately, with the new Vivid Colours feature in Leica Cyclone REGISTER 360 PLUS, this challenge is now a thing of the past.

Prior to the Vivid Colours feature, an inconsistent and frustrating mix of contrasts and intensities could result from multiple setups with varying contrasts, as seen in this image.

Understanding the Challenges of Point Cloud Colourisation

Colourisation offers a lot of value to a point cloud. When navigating, analysing, editing, identifying features, and extracting them, colour provides context and detail that are not available from the points alone. However, if a point cloud is comprised of multiple Setups, merged and colorised from proximal values in multiple RGB panoramic images, you get an inconsistent and sometimes frustrating mix of contrasts and intensities.

The multiple setups for a merged point cloud are captured from different locations, subject to varied laser return intensities, point densities, and lighting conditions. The resultant merged point cloud has non-homogeneous patterns and colours that are often difficult to understand. Only the most skilled practitioners, who have analysed many scans and have years of experience, may have been able to develop the heuristics to deftly surf point cloud intensity and colour representations without external references. Reality capture is growing rapidly, and there is a need to provide rapid and high-fidelity solutions for new entrants to the field.    

Some practitioners will resort to viewing the point cloud on one screen and the panoramic image on another to provide context. Or they process the point cloud as a colourised 3D mesh model. None of these approaches improves or optimises colour. A new approach analyses specific factors for each point, colour, intensity, and range from the vantage of multiple setups and selects an optimal colour to apply.

Vivid Colours can have a dramatic effect to the point cloud in downstream products like Leica TruView and Leica Cyclone 3DR. The point cloud becomes less grainy and speckled. The overall effect is improved clarity and "truer colours".

Introducing Vivid Colours: A Solution for Clearer Point Clouds

“Like a lot of point cloud collection in the field, inside, outside or mixed, the differences in light levels and scan density means that for any given scanner position, the exposure and the gathered image and the density of the collected point clouds can change from setup to setup,” said Guy Cutting, Senior Product Manager at Leica Geosystems, part of Hexagon. “Differences can be compounded by reflections on the walls, from shadows, and more. The problem the Vivid Colours feature addresses is point clouds being far less clear than they could be.”

This ongoing problem drove the development of this new feature in the most recent release of Cyclone REGISTER 360 PLUS. “It will process Vivid Colours but not show them. They will be written to universal file type LGSx in the export area and be visible in downstream programs like Leica TruView Desktop, Leica Cyclone 3DR, and more.” The optimised colours could then be realised in other standard point cloud export formats and provide benefits for any downstream applications.

The results can be dramatic. For example, due to lighting conditions, different glare patterns on a feature like a wall might result in grainy or bleached-out patterns. Vivid Colours can choose the optimal colour from non-affected areas of different scans. The point cloud becomes less grainy and speckled. The overall effect is improved clarity and “truer colours.”

Only the single unified point cloud is altered, not the raw scan. Users can easily choose to Apply Vivid Colours to Point Cloud within the Publish Options.

The Vivid Colours Process: How it Works

A homogenised point cloud can be comprised of many individual high-density and low-density scans. After registration into one bundle, overlaps are detected, and colours are intelligently selected from corresponding panoramic images. Vivid Colours takes this a few steps further.

Candidate colours for an individual with very high- and low exposure, determined from laser return intensity, are rejected unless there are no other options. Similarly, point intensities are evaluated. Often, the colour from the nearest scan setup among a group is the optimal colour to apply, so the range is considered. However, there can be cases where a scan from farther away provides the best colour. Multiple factors are evaluated, weighted, and averaged to determine the best candidate colour.

There's no degradation or decimation of point clouds. "De-speckling" or splatting techniques are not applied. The resultant point clouds, which can appear to be rather visually stunning, have simply had improved choices of colours for points applied.  

“The raw scans are not altered, only the exported, single unified point cloud,” said Cutting. “You also have the option of running Vivid Colours on individual scans. But we do not alter the panoramic images.” Of course, the next logical step could be to apply the homogenised colours to panoramic images, even re-running Vivid Colours for further optimisation. Truer colours would enhance downstream applications, such as a 3D mesh model.

Here is a side-by-side comparision of a point cloud without Vivid Colours (left) and with Vivid Colours applied (right). Locations with a wider range of potential high-to-low exposure will benefit the most from this feature.

Maximising Benefits with Vivid Colours in Point Clouds 

For a point cloud from a set of scans in an indoor location, with consistent lighting, you may not see much of a difference, but running Vivid Colours can still be of benefit, especially for conditions unanticipated or not immediately noticed on a cursory view of a point cloud—glare, shadows, points on the periphery of overlaps, etc.

Outdoor scans, and those that include both indoor and outdoor setups are where Vivid Colours can make a great difference. The uncontrolled lighting environment outside is dynamic, varying from day to day and time of day, with a wider range of potential high-to-low exposure conditions.

It’s important to note that the Vivid Colours feature can only be applied to structured scans from static scanners like the Leica RTC360, Leica BLK360, and Leica P-Series scanners. It can also be run on imported static scans. Unstructured scans, such as those with SLAM technology, like the Leica BLK2GO, Leica BLK2FLY, and Mobile Mapping Systems (MMS), are not (yet) supported by Vivid Colours.

Benefits go beyond visualisation. Improved visual perception fosters better decision-making. Automated point cloud classification and feature recognition, which include colour in respective processes, are examples of improved downstream algorithmic beneficiaries.

Reality capture and high-fidelity point clouds have become fundamental to the digitisation of infrastructure design, construction, and operation. Any processes that make them much more “real” are worth pursuing.  

For more information about Vivid Colours in the release of Cyclone REGISTER 360 PLUS 2025.0, check out the Release Notes.