Rectification of images of QR codes posted on cylinders by conic segmentation

Hoffmann

Computer Graphics Forum

2021

QR code is a widely used format to encode information through images that can be easily decoded using a smartphone. These devices play a significant role in most people's everyday lives, making the encoded information widely accessible. However, decoding the QR code becomes challenging when significant deformations occur in the label. An easy and quick solution to keep the deformation on a minimum level is to affix the label that contains the QR code onto a developable surface patch of a 3D model. The perspective distortion that can appear is efficiently dealt with during the decoding process. In recent years an alternative method has emerged. In the work of Kikuchi et al., the QR code is embedded onto B‐spline surfaces of CAD models to give more freedom in providing additional information. This method was further improved and extended by Peng et al. embed QR codes onto the surface of general meshes. This paper introduces a solution to embed QR codes onto the surface of general meshes without densely triangulating the selected area of the QR code. It uses the deferred shading technique to extract the surface normals and the depth values around the QR code's user‐given centre. We propose two methods for automatically finding the projection direction even when highly curved areas are selected based on the retrieved information while rendering the model. Besides, we introduce two methods needing a projection direction and a QR code centre to determine a size for automatically embedding the QR code. We propose patterns for decreasing the carving depth of the embedded QR codes, and we use the Horizon‐Based Ambient Occlusion to speed up the engraving process. We validate our method by comparing our results to the outcomes of Peng et al.

Section: Previous Workmentioning

confidence: 99%

Embedding QR Code onto Triangulated Meshes using Horizon Based Ambient Occlusion

Hoffmann

Computer Graphics Forum

2021

Proceedings of the 2018 International Conference on Mathematics, Modelling, Simulation and Algorithms (MMSA 2018)

“…In [11], it proposed a two-dimensional code correction algorithm based on conic segmentation. When the twodimensional code is skewed on the cylinder and we capture a two-dimensional code image, the two-dimensional code in this image is not the expected square which presented as a rectangular two-dimensional code.…”

Section: E Conic Segmentationmentioning

confidence: 99%

Design of Two-dimentional Code Anti-distortion on Conical Surface Based on Pre-stretching

You¹,

Cao²,

Gong³

et al. 2018

Two-dimensional code has shown its impressive performance on mobile payment and advertising marketing. To ensure that the two-dimensional code is correctly identified by recognition devices, the traditional two-dimensional code must be attached to the surface of the plane of the object. However, if attached to the surface of conical carrier, the image of the normal two-dimensional code will be compressed into distortion because of image projection, which will lead to identify problem. To this end, we propose a novel algorithm of anti-distortion twodimensional code on conical surface based on pre-stretching, to address the challenge of identifying two-dimensional code on conical carrier. According to the spatial geometric relation of the conic, pre-stretching the normal two-dimensional code image via inverse mapping to obtain the pre-deformed two-dimensional code which will be printed and then pasted on the surface of conic. Specifically, the image of the pre-stretched two-dimensional code in the projection plane of the acquisition device is just as the normal two-dimensional code, which will be correctly identified. To better demonstrate the method, we test it on experimental simulation.

A Correction Algorithm of QR Code on Cylindrical Surface

Meng

Huang

et al. 2019

J. Phys.: Conf. Ser.

When capturing a QR code on a cylinder, there may be geometric distortions due to the angle of the camera and the cylindrical deformation, which makes the QR code difficult to recognize. To solve this problem, a correction algorithm for QR codes is proposed in this paper. First, the boundary of the QR code on the cylinder is extracted by a morphological algorithm and geometry calculations. Then, the feature points on the image are accurately located. Next, the standard size of the QR code is determined by using the cross-ratio method in descriptive geometry. Finally, the image is corrected by perspective projection. It is proven that the algorithm can correct the distortion of the cylinder image effectively, and it has the ability to properly identify cylindrical QR codes.