3D Scanner System for Stair Reconstruction

The industry partner Weitzer Parkett produces parquet and stair claddings. Each stair cladding can be made from different types of parquet. They have professional customers – mainly floorers who are also installing wooden stairs at private and public premises. With their application “3D Measurement for complex constructions” as specified in the Vision+ application document, it is intended to develop a 3D measurement system for stairs in Vision+. The 3D measurement system is able to capture raw stairs – before application of the wooden cover – in order to model the shapes of the covering elements (boards / planks) for automatic production.

The scene to be measured is captured by a portable active depth sensor. Hereby, a sensor system was built consisting of COTS industrial computer vision components (three industrial cameras, synchronization box, infrared band-pass filter, lenses, mechanical set-up, power supply) combined with the projection unit of a commercial 3D sensor (infrared speckle pattern) and control software that is able to capture synchronized videos with about 15 frames-per-second (fps) in full resolution of 1380 * 1024 pixels.

Stair capture process for wood cover modeling.

Portable depthsensor system consisting of COTS components.
Raw data derived from stereo sensor (left, right: stereo images for geometry derivation, center: additional image for texture).

A workflow for dense distance measurement integrates the raw data to a coherent 3D model of the scene. The achievable accuracy lies in the mm-range and is mainly dependent on the resolution of the cameras, respectively the applied sensors.

The workflow includes:

  1. Lens distortion correction, stereo matching, artefacts removal and distance image generation.
  2. Dense Stereo Matching: SGM (semi global matching) was used, together with the necessary epipolar rectification.
  3. Depth map fusion that is optimized for the noise and outlier characteristics of the new depth sensor.
  4. Assessment: The 3D model is segmented into geometric primitives (tread and riser for stairs) and the data is prepared for further processing in CAD programs.
Overview on 3D workflow.
Overview on 3D workflow.


Textured 3D model of a staircase obtained from a fused depth video stream.

Derived CAD-model of staircase.

The 3D-scanning system is able to automatically combine individual measurements and can thus measure a larger volume by generating a dense net of measurement points.

The system offers high precision and is ideal for any application that requires an accurate 3D capturing of the environment.