3D Photogrammetry

Treework Environmental Practice are innovators in the world of 3D Photogrammetry of trees using drones.

We are fully insured to undertake this work which utilises the latest light weight drones to capture 3D models of trees. Using a sub 250g drone gives us the advantage of reducing the requirements to fly which means that we can respond quickly and access even more sites and trees.

Photogrammetry is the process of taking a series of photographs of an object, from a variety of angles, and stitching them together to create a 3D computer model. Some of the benefits of applying drone 3D modelling and photogrammetry to trees are:

• It can help project design teams to visualise trees in a whole new way!
• The outputs provide accurate 3D models of tree opportunities and constraints in relation to a proposed development.
• The information can be used as an additional tool to help Planning Officers to pre-visualise and understand development proposals near trees.
• Enhance existing surveys: correct application of surveying using a drone can provide an extension of the Visual Tree Assessment approach to inform risk assessment and management recommendations.
• The system will enable accurate recording of measurements of the aerial parts of a tree to inform the design process and analysis of likelihood of failure.
• Digital tree pruning illustration. It is possible to model a ‘before’ and ‘after’ visualisation of pruning before contractors commence work.
• Can be used to generate visualisations to help show and inform expert witness case work.

Trees are complex vertical structures that can now be accurately modelled using this 3D photogrammetry. We are already applying our knowledge of drones and photogrammetry to add value to existing projects. Below are a couple of examples of how we have used drones and photogrammetry to understand more about trees.

This incredible English oak tree is supported by 3 cables/ground anchors and is located next to a low use road. Several veteran features can be seen to some extent from ground level. The video you can see was made using photographs taken by a sub 250g drone. By producing this 3D model, it has enabled us to better understand the extent and interrelationships of the features and the history of branch failures from a new perspective.

The advantage of producing a 3D model is that it can provide extra information to inform an ongoing tree condition assessment. It can also be used to accurately measure aerial parts of the tree and can serve as an interim step in deciding whether to commission a climbing inspection. In essence, if you require more information than you can collect from a ground level visual tree inspection, 3D photogrammetry is worth considering.

Treework has been exploring the use of photogrammetry to extend visual tree assessments with a view to helping inform tree risk and management recommendations.

Visual tree assessments from ground level will typically provide preliminary information about tree health and condition. However, as you can see from the early stages of this animation, it can also be limited. A full inspection of defects on the upper side of branches and high up in the crown cannot be achieved.

There are times when it is appropriate to recommend a detailed climbing inspection to help inform tree risk assessment and management, but these can often take a long time to arrange and the quality and extent of information provided by climbing arborists can vary considerably, even with clear instruction. This can lead to uncertainty and could result in poor management.

With photogrammetry it is possible to quickly assess the extent and significance of defects from any perspective you require. Defects can be assessed ‘in the round’ with the associated parts of the tree. Accurate measurements can be recorded and compared with known failure criteria to help understand the likelihood of failure. Models can be shared with colleagues for a second opinion. They can also be recaptured over time and then compared to monitor development.

On this large, mature beech tree, located in a frequently used area, it was unclear whether a recent branch failure was due to deep seated decay or if the mechanics of failure had compromised the structural integrity of the adjoining stem. More information was needed to understand what was below the old, torn out wound. We therefore used a drone to collect visual data from different viewpoints.

The resultant model produced for this tree provided sufficient information to determine that the recent branch failure was not because of decay and failure does not appear to have compromised the adjoining stem. This means that the arboricultural consultant assessed the tree as having a higher risk index (lower level of risk) than it had from the preliminary visual assessment. It is a good example of how photogrammetry can help to inform tree risk assessment – in this case, helping to retain the tree.

It should be acknowledged that there are limitations to photogrammetry: access and permission to fly, species type, twig density, weather conditions, hardware and software limitations are just a few issues that can compromise the quality and useability of a photogrammetric model. However, with the setup that we have developed, the benefits appear to outweigh the time investment to manage these, and the outputs are not only visually fantastic, but also add real value to many of the services that we already provide.

Treework Environmental Practice continues to explore areas where photogrammetry can be applied in arboriculture, and we are happy to share what we know. Please feel free to contact us for more information or to discuss how the information that we can collect with our drone, can help you to better visualise, manage and solve problems relating to your trees. Email us info@treeworks.co.uk