EDIT: Autodesk have discontinued Recap360 since this article was written, but you can find out more about making 3D models from digital images in these other great posts on the blog.
I’ve been creating a fair number of 3D scans lately using Autodesk’s free Recap360 service and many people have asked me about my workflow. It’s really not a difficult process and with this tutorial, you will be able to:
- Create a 3D Scan using a digital camera and Autodesk Recap360.
- Crop the model in Blender.
- Publish the model to Sketchfab and optimize the presentation.
Don’t be discouraged by the length of this tutorial! After doing this a few times, most of the things here will become second nature. I typically need about 30 minutes to capture, upload, clean and publish a model. Not bad for free tools 🙂
The beauty of this approach is that you don’t have to invest anything! If you have a digital camera or even a smartphone then you’re all set to get started.
And before you ask: yes, there are other apps available to achieve this. To keep things simple I’ll just focus on Recap360, but the principles in this tutorial will apply to those as well.
Choosing a subject
So how does 3D ‘scanning’ without a scanner work? This software works with a technology called ‘photogrammetry’. An algorithm goes through your photos, calculates the camera positions and perspective for each one, and from there regenerates the geometry of a three-dimensional model.
The software needs to ‘understand’ how the photos relate to each other. For this, you need to provide enough overlap between pictures. About 50% overlap is more than enough in most cases.
It also needs to ‘see’ enough detail in your model. Models that have only one color (like a clean white table) or models with very dark shadows will confuse the software and you may see weird shapes as a result.
Reflective or transparent surfaces are also very hard to process – stay away from those.
For this tutorial, I’ll use my ‘Box of Dinos’ as an illustration. I found it in my sons’ room and I liked the chaotic shapes and colors. I wasn’t sure that 50 pictures would cut it (the limit of the free version of Recap360, read on), but I was pleasantly surprised with the result!
I’ve learned that I get the best results when shooting pictures outside with overcast weather – this way you’ll have nice and even lighting without harsh shadows. Avoid shooting in direct sunlight as this usually makes it hard to capture darker parts of your model. Also, you’re much more likely to cast your own shadow on the model when you’re working in bright sunlight.
The free version of Recap360 allows you to use up to 50 pictures, so make the most of it! (You can pay ‘credits’ to allow for more pictures and to generate a higher-resolution mesh).
For the first pass, walk around your model in a circle, each time moving about 45 degrees. Shoot the objects from three different heights while keeping your camera aimed roughly at the center of your model. You should now have about 24 pictures, so we have 26 left.
Here’s a schematic of my camera path:
For the second pass, find areas that might have been covered or hard to reach. Also, I tend to zoom in on parts that I think require extra resolution.
Take more than 50 photos – we’ll be reviewing them after this.
For an example of parts that are hard to reach, check out my embed above and try to navigate between the dinos. I actually carefully stuck my camera between some models to snap pictures from below, and I took some pictures through the holes on the sides of the box.
For more tips on selecting a good camera, model, and lighting conditions, see our tutorial ’How to set up a successful photogrammetry project’.
Review your photos
Now if all went well you took more than 50 photos. Before uploading them, review them carefully and pay attention to the following:
- Is this shot out of focus?
- Is this shot too similar to another one?
- Is the lighting in this picture very different from the others?
Keep discarding photos until you have 50 left.
Processing with Recap360
Now create a free account on Autodesk Recap360, and click on the ‘Photo to 3D’ option on the homepage. Now simply drag your pictures into the browser to start the upload process. This may take a while, especially if your camera is 10 megapixels or more.
Click ‘Next’ and give your project a name. As you can see the free version offers limited resolution, but it’s often good enough for my purposes.
That’s all! Now submit your project and prepare to wait – as the processing is all done in the cloud there really is no way to predict how long this is going to take. Best case: less than an hour. Worst case for me so far: about half a day. Recap will send you an email when your model has finished processing, and you can now download the result as an OBJ file with texture maps.
PRO Tip: you may want to clean out your Autodesk A360 Drive every now and then to remove old photographs and scans – here’s how.
I like to process my models with Blender. After unzipping the downloaded model and importing the OBJ, this is what I see:
Of course, Recap360 does not know which part of the model I’d be interested in, so it gives me everything it can reconstruct. It’s up to me to crop the model and leave only the interesting bits.
First, though, I’ll rotate the model so that it’s placed flat on the floor.
Then, I’ve found that the quickest way to crop a model is by using the ‘bisect’ tool. Go to top view, enter edit mode for your model with TAB, hit SPACE, and enter ‘bis’. The bisect mode works by drawing a cutting plane on your model, so just drag a line from top to bottom:
By default, Bisect will cut your model in two, but it can remove the unwanted part by selecting ‘Clear Inner’ or ‘Clear Outer’ in the tool options. Whether to use ‘Inner’ or ‘Outer’ depends on the orientation of your cutting line, so just experiment a little.
Now just repeat a few times until you’re satisfied with the result.
Upload to Sketchfab
Blender comes bundled with a really nice exporter. Just enable it, enter your API key, and hit ‘Upload’ to send the model and its texture maps to Sketchfab.
Alternatively, you can save your cleaned model as an OBJ file and zip it together with the texture maps. Drag the ZIP file onto the Sketchfab site to start the upload process.
Cool, so now you have your model on Sketchfab! You’re not done yet though 🙂 Here are a few quick and final steps you can take to supercharge the presentation:
First, click the orange ‘Settings’ button on your model page and select ‘3D Settings’. Switch from the default ‘Lit’ lighting model to ‘Shadeless’. Your scanned model already contains light information, after all!
Second, enter the Post Processing Filters and add a tiny dash of Sharpness (about 20 usually does it for me). This makes your textures much crisper and really brings out the details.
That’s quite a difference, isn’t it? There’s much more you can achieve with the 3D settings – watch this excellent video tutorial by Thomas Flynn for some pro tips.
Finally, make sure people can find your cool model. Return to the orange ‘Settings’ button and select ‘Properties’. Next:
- Select the right model categories and tags to make the model show up in the right galleries.
- Add a nice description to tell your viewers about this project (you can use Markdown to format it).
- If you’re feeling generous, allow people to download your model!
Please let me know if this tutorial helped you and how I can improve it, and share your results below!
If you enjoyed this, then check out my other scans here at Sketchfab!