CS-3D-Api | Semi-global matching
CS-3D-Api now has a GPU implementation of an alternative 3D reconstruction method to the existing block-matching (BM) approach. The approach is based on the semi-global matching (SGM) algorithm, which is very accurate at object borders, fine structures and in weakly textured terrain. It combines concepts of global and local stereo methods for accurate, pixel-wise matching at low runtime.
3DPIXA: Limitations of block-matching algorithms on depth reconstruction
This white paper gives a comprehensive overview on the limitations of the block-matching approach in height reconstruction for passive stereoscopy. It describes a variety of different artefacts that appear at certain image features. The occurrence of the artefacts is explained by means of the algorithms underlying mathematical model which is introduced in the first chapter. Images captured with a 3DPIXA exemplify the visual appearance.
Spectral sensitivity curves of cameras
When designing spectral camera sensitivity curves for multi-channel cameras, various aspects have to be considered. In addition to the feasibility of the found function, these are the saturation behavior and the signal-to-noise ratio under the assumed lighting conditions. This article focuses on the colorimetric re-production properties of the filter functions. The R-Matrix theory propagated by the color scientist Jozef Cohen is used as an instrument of investigation.
Image warping caused by heat-induced turbulence
The cause for warping in images captured with line scan cameras due to heat induced turbulence is explained and a method for measuring the magnitude of the distortion is described.
Application specific color calibration with truePIXA
The aim of this work is to illustrate the dependence of measurement performance of multi-spectral imaging systems on the type of color calibration used. For application-specific color calibration, high performance can be achieved. If a non-adequate color calibration is used, the measurement performance might drop considerably. These effects are demonstrated empirically by means of textile and paper measurement applications. The underlying theory for the measurement performance drop is explained briefly.
Inspection of bulk material with allPIXA wave and prism camera
The aim of this work is to compare the trilinear line-scan camera allPIXA wave with a prism based camera with respect to bulk material inspection. Traditionally, prism-based cameras are often selected over trilinear cameras when it comes to bulk material scanning, as the inherent line-shift of a trilinear camera can only be corrected for when the object scan velocity is known. We demonstrate that this traditional approach is not always necessary if the right trilinear sensor is selected and operated in binning mode to average multiple pixels.
3DPIXA: Coaxial Brightfield Illumination for 3DPIXA Applications
Choosing the right illumination for the application is critical for acquiring the high quality images needed for calculating 3D data. We compare the imaging results of a directional coaxial brightfield illumination with a Corona tube light in terms of color image quality and height map for different samples. It could be shown that for material that exhibit considerable amounts of subsurface scattering, coaxial lighting geometry benefits the 3D measurement using 3DPIXA.
3DPIXA: Options and Challenges with Wirebond Inspection
Inspecting wire bonding processes inline is currently one of the most challenging tasks in machine vision. Traditional inspection is performed on 2D images, color or grayscale, and consists for instance of wire tracing, Bent and broken wire detection, Wire solder spot / wedge analysis, Wire attendance check. 2D inspection is insufficient for some tasks and 3D information is required.
3DPIXA: Repeatability Measurements
The procedure for measuring camera repeatability is described and illustrated by example of a 15µm 3DPIXA camera module. It is elaborated how to distinguish repeatability of the camera, and repeatability of the entire scanning system. Practical information is given regarding how to analyze scan data and how to account for measurement bias.
Optimal lighting for line scan camera applications
The light factor is often neglected when discussing high performance image processing systems. Every brilliant image requires two things: an excellent camera and excellent lighting. The following article offers good advice for the selection of an optimal lighting solution and important practical tips.