Using Drones to Digitize Built Heritage

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Hi there, I’m David @Archventure and I have been working with 3D for over 10 years. I am not part of an organization, but I am working on building myself a portfolio with good references to have my own business in the field of photogrammetry.

Background

It was when I started to study architecture at ETH Zürich. 3D modeling and rendering quickly became a passion of mine. I loved how efficiently 3D could be used to show ideas in a precise way and make them understandable to everyone. Often 2D plans can be hard to read and imagining the feel of a 3D Space just by looking at floor plans is tough. Building physical models, however, is very time consuming and expensive. Those are some of the reasons why I preferred to work with 3D Models instead.

Quickly I learned how to use CAD software like Archicad to visualize my projects, render them in Cinema 4D and compose in Photoshop. I got good at it and always tried to improve my skills.

During the first years of my studies I heard a lecture about the possibility of composing multiple aerial photos into an actual 3D Model. It was very fascinating to me but I hadn’t put any further thought into it because it seemed to be out of reach and there were no such things as consumer drones back then. But I had the feeling that someday I would pick up this topic again.

After my masters graduation I decided to go travel around the world on my motorbike. I was on the road for 2.5 years and in that time I was focusing on photographing, filming and editing videos about my journey. During my travel I bought my first drone to enhance the quality and perspective of my output. It was the newly released DJI Spark. The compact form factor was ideal for my type of travel.

I returned at the end of last year from this journey and was working this year as an architect in an architecture office in Burgdorf, Switzerland. I was working on the 3D visualizations for a couple of projects since no one else in the office had the skills to do it. I was also able to use my little drone for work to capture photos of facades for preservation of evidence.

I got a little bored from the work of rebuilding the surroundings according to 2D contour line plans for housing projects in order to merge them accurately into a photos perspective. The results didn’t satisfy me as they used to. It just didn’t seem precise enough anymore. There was too much guessing involved during the reconstruction of the environment and also in fitting the actual 3D Model into the perspective of a photo. I was craving something more accurate.

That was when I remembered the lecture from my studies when I heard about the possibility of generating a 3D surface from actual photos. I decided to catch up with the latest developments and possibilities.

I mentioned to my boss about wanting to use photogrammetry in order help with the architectural projects in more precise planning and visualization. Surprisingly my boss wasn’t very interested in it. I think it was because he hadn’t heard about photogrammetry before and suggested that 3D-Scanning would be something rather expensive. I decided not to annoy him with my ideas for longer but get more into it by myself. Since then I’ve been practicing my photogrammetry skills and was able to improve my skills with every scan. I also explored the possibility of scanning small objects like fountains as well as large scale terrain like castles or the old town of Bern city.

Now I feel confident offering my service in 3D scanning to any person or company who is interested in visualizing physical objects as virtual 3D models.

Cultural Heritage in Switzerland

Cultural Heritage is a big part of the Swiss culture. If you have ever been to Switzerland you probably noticed that the cities and villages look like something out of a fairy tale. This isn’t just chance or lack of finance to build skyscrapers, but the strong will to preserve our cultural heritage. Many buildings and places are protected by one of the many government institutions for the preservation of cultural goods. It is not allowed to change the appearance of such objects. Any changes always have to be approved by an officer of that department. Even renovations have to follow strict rules. That’s the reason why Switzerland looks kind of ancient on the outside, but under the hood one will find the most up-to-date technology.

I am glad to be able to see so many buildings from the past and record them the way there are. I hope someday my work will be able to help preserve our heritage for future generations.

Each year 3D seems to become more important and accepted and I believe 3D scanning will be a part of this. It helps to make things more precise and capture objects exactly the way they are.

Workflow

Choosing the right tool.

Depending on the size of the project a handheld camera is not enough to capture the desired scene from all angles. For single houses or whole neighborhoods a drone is required to get the shots from above. For single buildings I prefer to use a small drone which can get into smaller spaces and doesn’t draw too much attention or make people uncomfortable. So I often use my DJI Spark. It is a very small drone which only weighs 300g. The downside of it is the flight time of less than 15 min and also the lack of waypoints which allows planned and automated flights. But for those single objects waypoints are not necessary. I think with a manual free flight I can get better results. I also use a compact camera (Panasonic Lumix TZ110 with a 1” Sensor) in addition to the drone to capture the views from below and get much more detail. This makes for example the overhang roofs look much more accurate in a closeup view of the final model.

For a large scale project it’s great to have a drone with capability of waypoints. With this function its possible to set up the desired picture overlap, camera angle as well as the flight area before the flight. For this purpose I had great results with a DJI Mavic Pro.

Choosing the right time.

A good 3D model is a versatile 3D model. This means its best if the final 3D model doesn’t contain lighting information and is evenly lit from all sides. If at the shooting time you find yourself with strong and long shadows, then they will be also baked into your 3D model.

This is often inevitable but with some luck and planing the results can be improved. The best conditions for shooting are at an overcast day. There won’t be any hard shadows and the object is evenly lit from all directions. If you can’t wait for that day, then try shoot at midday when the sun is the highest. This way your shadows will be very short and you will get quite evenly lit facades.

Another possibility is to shoot just after sunset. The result will be similar to an overcast sky. But you need to get that footage quickly before it gets too dark and the pictures get blurry or grainy.

If I don’t miss capturing all corners of the object properly I can move on and feed the images to my computer to align the pictures and generate the point cloud.

The old city of Bern

I made this model with the help of a DJI Mavic Pro. 1016 pictures were used for it.

  1. I started with a rectangular large scale nadir grid with a vertical view at about 115m altitude.
  2. I chose a part of the city where I wanted to show more detail. It was the bridge and the surrounding buildings with the church. I flew a double grid with less altitude and the camera at an angle to capture more vertical details. The double grid ensures that images are taken from multiple sides.
  3. To get some more details out of the church I circled around it.

Child Eater Fountain

This fountain is located between historical buildings in the busy pedestrian area of old Bern in Switzerland. Due to this reason it wasn’t possible to use a drone, so I did all the necessary shots with my compact camera.

Ancient Temple in Ayutthaya

This is one of the many temples you can find in ancient Ayutthaya, Thailand’s former capital city. I shot this at sunset and was hoping I could get some good lighting even in the shady spots. I’m quite happy with the outcome. I only used the DJI Spark and a compact camera. With the Spark only free flight is possible so the picture positions are quite random. But I still started with some higher altitude shots to cover the area, followed by close up shots with a camera angle to cover the details. I used the handheld camera to get the angles which the drone can’t get and to add the final touches to it.

Another example of a pretty swiss castle

Sketchfab

To make the models look even better Sketchfab offers some great tools. In the 3D settings I usually set the shading to shadeless since the models already contain that information in the texture. In the post processing filters I typically use the sharpness filter to bring out even more details. Most models don’t require more. Sometimes I add the depth of field, SSAO or grain filters very discreetly.

Getting into 3D

Anyone who is interested in 3D should learn about the basics of modeling and texturing first. There are plenty of tutorials online, just have a look on YouTube first. That’s important as the first step is to find the right software. After you get used to one you will most likely get stuck with it. There is a lot of 3D software out there and the choice isn’t easy since many of them do the same but slightly different, each with a different focus and approach.

I can recommend Cinema 4D since it’s easy to get into and has many features. Also look into Blender; it’s free and open source with many professional features and has a strong community. You won’t have trouble finding good tutorials. Don’t forget to have fun and challenge yourself.

Thank you for your interest in my 3D models and thanks to Sketchfab for making it possible to share them in an easy and beautiful way online.

You can see more of my models on Sketchfab or visit my website.

 

About the author

David Kretz

Founder of Archventure


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