Following on from previous posts and specifically this first post on the iPhone 12 Pro where I made some bold claims, oh and have a look at the ‘Millennium Stone’ scan I have done here. I have written this post as brief set of tips and tricks that have seemed to work for me when 3D scanning. The scanning tips should work with all apps I’ve used so far for the iPhone.

Now as usual terms and conditions apply these are my findings and what I have found works for me. Before you use any of my workflows in the ‘real world’ or for ‘work’ please test it first for you.

This took several attempts primarily because of our cat!
Plan your scan

The general rule for scanning is to scan like you would paint a room slow sweeping over an area so that you don’t have to go back and rescan anywhere is best. For any object, building, or landscape you need to plan your route. With objects clear a space place the object in the centre and ensure you can walk around it (this can be harder than you think!). With buildings inside or out avoid people (or pets that move) ensure your path through or around is clear enough for you move without tripping. For any scan avoid mirrors and really reflective surfaces if possible (turn them over?) or be prepared to edit afterwards. These surfaces trick the sensor into seeing geometry that isn’t there.

The following is guidance I have found might be useful to those starting out. As usual this blog is really a glorified notebook for me, I hope it might be useful to you too (it’s just not guaranteed!).

  • Objects (indoors or outdoors)
    • Ensure as much as possible that the object you want to scan is placed where you can gain access to all sides of it. 
    • Really small objects (like a phone or pens etc..) don’t scan at all well, do not expect fine detail. Remember the sensor is really for AR applications within rooms.
    • Rectangular shapes work best but they will still look wobbly (think cereal boxes)
    • Shiny objects or glass objects do not scan well at all. 
    • Place in well lit room and ensure you don’t have really strong direct lighting the cause sharp reflections. 
    • Avoid object making too many or to dark a shadows as this makes the textures look crap.
    • Try when scanning to move around the object in one direction and whilst you can ‘rescan’ over areas you’ve done before it can cause problems.  Know when to stop! 
    • Be prepared to do this a few times to get a good scan
  • Buildings (indoors)
    • Plan your route
    • Ensure house pets or humans are not in your way (or get them to stand behind you when scanning)
    • Clear objects you might trip over (yes I trip a lot)
    • Scan in a slow painting type motion around a room.
    • Whilst I have scanned my whole house in one go, scanning individual rooms is easier to manage (especially if you make a mistake)
    • If you are scanning a whole house internally, the transition from upstairs to downstairs is tricky! Practice that part first and see what scan direction allows for better alignment of floors. My first scan looked okay for upstairs and downstairs but actually the two floors were not aligned because I made a mistake scanning too quickly on the stairs….
    • If you have a large building divide the scanning process up. It is easier to manage and there is software to allow you to join meshes later.
  • Buildings (outdoors)
    • Similar to the above guidance!
    • Take into account weather! A sunny day is nice but I’ve found bright but overcast days better. White and shiny surfaces do not always scan well in bright sunshine.
    • With historic buildings vegetation and general junk can get in the way. Try and clear as much as possible or just be aware some parts of the scan make look lumpy.
    • If you can do a complete scan around the building it is best. I have done this and it is satisfying when you can join it all up! On a practical note it is also easier to manage for measurements etc.. later. However if you can not split the scan into easy to understand parts, if you are going to join the scans up later ensure you scan with overlaps to the next section. These overlaps must have easy to identify features so you can match scans up easily.
  • Paths and tracks (outdoors)
    • Again similar guidance to above, plan your route a little.
    • Bright but overcast days work better for me.
    • Avoid scanning between very contrasting light/dark areas if you want a good quality textured model.
    • If you want to scan at a good speed a trick I’ve found is to hold the iPhone facing backwards and to the floor slightly. This allows you to walk faster! Scanning with your iPhone facing the direction of travel does mean you get to choose scan paths and features but it also means you are having to walk slower.
External scan of our office (a historic converted Barn) this is a screen shot of the scan hosted in ArcGIS Online. The measurements are accurate within a couple of centimetres here, and show a good use of determining levels relative to other features.

Software

Okay I have a few free and paid for software tools I have used to view/measure/process the scans. These are Windows 10 programs (sorry I do not own a Mac!). I intend on doing some posts on how to use these in a workflow for processing scanned data. If you are looking for iPhone applications I sort of recommend click here [updated 2020-12-22].

  • MeshLab (free)
  • CloudCompare (free)
  • SketchUp (paid but there is a free version, I use the pro/paid version though)
  • ArcGIS Pro (paid, no free option but obviously free trials, there is also a cheap licence for home use)
  • Owlet (for very quick renders no longer available and yes I know I am misusing it a little!)

That is it for now, in Part 2, I hope to write about processing and publishing the scans. If you have any comments or questions leave the in the comments section, I reply eventually! Alternatively connect with me on LinkedIn or twitter!

4 COMMENTS

  1. I’m so pleased to find your blog posts. I am trying to see if I can use lidar scans from my iphone for openstreetmap surveying but the few workflows I’ve tried aren’t working great yet. I’d prefer to minimise the amount of processing done on the phone itself, but it’s fairly new ground to me. I cant even find an application that will take the obj file and the snapshots/json sidefiles from 3dscanner app and rasterise it. I could probably do it all manually, but i feel all the information is there already to not need to.

    I look forward to reading part 2!

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