Golf Course Photogrammetry

Due to the Coronavirus pandemic, during periods of lockdown Golf courses have been forced to close to players and members, but this has given ground staff the opportunity to undertake work on a scale they wouldn’t normally be able to do. V1AS joint business owner Dave and shareholder Damon are keen golfers and members of an excellent North West based golf club. Ensuring that Covid precautions and social distancing measures were strictly adhered to, we were able to use the down time to take our drones on to the course and obtain large scale models to provide invaluable test data and further develop our photogrammetry solution.

We decided to utilise all of the drones over a couple of days to see how each of them would compare from a camera and battery perspective as it’s not often you get full access to large areas of private sites such as golf courses. We’ve had a DJI Matrice M210-V1 and a Matrice M210-V2 for quite some time, but recently added two DJI Mavic 2 Enterprise Zoom drones and Smart Controllers (see our equipment page).

Operating a drone business only in the summer time and in fair weather conditions would be utopia, but unfortunately to be able to deliver a reliable service to customers, and to sustain a viable business, operating in weather that is far from ideal is the norm. Given that our opportunity to own the course for a couple of days was well into the winter season, this was a real chance to see how the drones and cameras would handle whatever weather was thrown at us, and how it may effect the delivery of the product to a customer.

Image quality and consistency is really important in photogrammetry, and operating in winter this was always going to be an issue due to factors like the low sun. If you’re waiting for that perfectly clear day to map a large project then here in the UK as we all know, chances are you’ll be waiting a long time. When the sun is out it casts long shadows from structures and when it is behind cloud, the light drops considerably. This has a significant impact when mapping large areas in terms of consistent image quality over the time. Available daylight is also an issue in winter because no sooner are you setting up and getting going, you’re already running out of quality light.

Winter sun shadows hamper aerial shots for photogrammetry

Having a number of drones in our fleet we were able to maximise the time and light available by having two drones in the air at the same time. On a sizeable project we would generally have two operators and an observer to ensure safety and maximum use of airborne time. To get the best quality 3D models possible, as well as photographing from the vertical, it is important to take a series of images from at least two oblique angles to ensure that there is as much image data as possible for processing software. This increases the flight time as the drone will have to make multiple passes for each photographic angle.

The speed at which the drone is flown can have a significant impact on the image quality when operating in poor light. When the light is low the camera shutter will be open for a longer period when taking each shot, and over certain speeds this will appear as motion blur on each recorded frame and have a detrimental impact on the quality of the final 3D output. The time we spent operating over the golf course was invaluable as the conditions varied over the days we were there. As a result we were able to record optimum speeds to fly our drones on future projects to obtain the best images possible.

As we have DJI Crystal Sky displays integrated with the Cendence controller for the Matrice drones, and DJI Smart Controllers for the Mavic Enterprise, we use the DJI Pilot App for the autonomous flights when doing Photogrammetry. These have ultra bright displays designed for outdoor use so it was really easy to build flight plans on the fly rather than indoors or struggling with the reduced brightness of mobile devices. The software is really intuitive and user friendly, and the information such as flight time left versus battery time available was very accurate. As we were operating over open green land, we could really test this accuracy with large area mapping which would require pausing a mission several times to change batteries. This testing gave us the confidence and trust in the equipment that now allows us to operate on a large scale more efficiently, reducing our time and overheads, and as a result reducing costs to the customer.

With a career background in a technical I.T. sector I enjoy the software side of photogrammetry, and have spent many hours with tools such as Pix4D and Drone deploy understanding the differences and which project types each is suited to. I chose to use Pix4D to process the golf course data, with impressive results. The software suppliers offer cloud based and local data processing. Each has it’s own benefits but we opted to purchase high performance gaming spec laptops to have the flexibility to process data locally in the field. Image data for aerial mapping projects can be extremely large and as a result it can be time consuming to upload to the cloud over mobile data for processing. During testing we were able to operate the drones, process the data and produce complete models in Pix4D without having to leave site, and in just a few hours.
This testing also showed that we can provide the customer with real time data such as area, volume, distance, elevation and more more, on the fly and anywhere without the need for external facilities such as mobile networks and without the need to take the data away for processing, potentially reducing overheads, time and costly delays for the customer.

Area, Volume and Distance Measurements Produced Quickly and Accurately

We were lucky enough to spend time with the head green keeper of the golf course while we were there to learn how our technology could be useful during the construction, maintenance, and re-development of golf courses. We took away some invaluable knowledge allowing us to develop services utilising data obtained from photogrammetry that we hadn’t considered previously. Providing the ability to manipulate the 3D models to show how potential course modifications will look before work actually commences such as moving bunkers, or removing a tree line for instance.

Although it was extremely cold at times and the weather was challenging, we had a very worthwhile few days and gained experience that will certainly allow us to deliver an extremely high quality and cost effective solution to our customers in all industry sectors.

Providing 3D surface Area Data for Bunker Augmentation

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