Indoor Mapping of a House with a Phone Camera

Indoor Mapping of a House with a Phone Camera

Location: Ljubljana, Slovenia
Date: June, 2018

This project demonstrates how to utilize 3Dsurvey software to map the interior of a house for installation and infrastructure. An architectural firm used a smartphone to capture 2D images and processed them with 3Dsurvey software to automatically get geo-referenced and highly detailed 3D results.

Dense point cloud house

The future of indoor mapping - Are traditional methods ready to be upgraded? Traditional mapping and surveying methods are being replaced by digital approach. This does not mean they should be left out of the picture. Mainly it motivates us to start trusting and relying more on modern technology and digital solutions.

With the use of photogrammetric software and fully digitized actionable data the client saved more than 30% of time in the field and was able to generate highly representative data along with 3D visualization and interior plan.


Utilizing 3Dsurvey's orientation and geo-referencing wizard the client was able to position all cables and infrastructure with a cm-grade accuracy. Such data massively helps with the finishing of overall construction works and with maintenance later in life-cycle of the house (for example: in case of drilling holes, etc).

Local GCP points

To get the most accurate data, GCPs (ground control points) were used for orientation of the 3D model. Because of GCPs there is no need to use any expensive measuring equipment such as total station or GPS devices that are hard to work with inside a house (lack of GPS connection, etc). All we needed to do to measure GCPs was to define the coordinates with the aid of a measuring tape. Measurements were written in *txt file which got imported into 3Dsurvey.

To avoid getting results shown in negative Y axis, elevation is best set to a position above ground level - 100m in this case.

Scan from Ground Floor to Upper Floor

On the ground floor 77 images with 75-80% overlap were taken. Details must be seen on at least 3 images for the automatic algorithms to perform properly and deliver precise and accurate end results. The same workflow was repeated in the upper floor (115 photos were taken).

Indoor Hand Shoots

To achieve the best results it is important to follow a certain workflow and to position yourself correctly inside a room.

Try to avoid positioning yourself in the center of the room and taking pictures around you. It's way better to position yourself against the wall and take pictures in half-circle. See the screenshot below for a better representation of camera positions in this particular project.

Indoor mapping camera positions

Because the floors are connected only with the staircase it would have been very difficult to take photos of the entire house, so we did it in two separate projects. For the GCPs we used the same coordinates, we just added 3m of height, since the height of the ceiling is 2,70 m + the thickness of the panel 0,3. The orientation is working well in this way and it fits together. 

Room Scan from Photogrammetry

This resulted in 3D point cloud that enables the users to measure the distances between the different elements in the house – for example distance from different cables in the wall. It also enabled us to have a documented cross-section of the different layers in the house for future use and we will be able to see the specific of the desired layer in case we will need it. 

Measure anything you like

The finalized 3D model and corresponding outputs served as a basis for ArchiCad drawings, modelling of the interior and designing furniture. A detailed digital map - that's measurable and geo-referenced - of electrical and plumbing has been generated for further decision making and detailed documentation.

Technical specification of project:
 

  • Tool: Smartphone - Google Pixel I.
  • Camera: Integrated 12,3 MPIX
  • Orientation: Local coordinate system - 3 GCP points
  • Number of images: 182
  • Flying height: / Hand shoots
  • Time of processing data on a high-performance computer: BA: 6 min, Orientation: 15 min, Dense reconstruction: 6h (on Extreme). Dof, volumes, profiles - on the GO.
  • DOF Resolution: no orthophoto, just point cloud
  • Area size: 90 m2