In this paper, a new method for extracting primitives of a regular texture via wavelet transform is provided. Each primitive is restricted to be a parallelogram. The main work of the proposed method is to extract the two displacement vectors that form the primitive of a regular texture. A contrast-based criterion is used to select appropriate subimages obtained from wavelet transform for detecting displacement vectors. An edge thresholding method is then performed on the subimages selected to locate edges. Based on these edges, Hough transform is applied to extract the displacement vectors. The proposed method is quite efficient and can get more accurate results for displacement vectors when comparing to traditional co-occurrence matrix based methods. Synthesized textures are provided to show the effectiveness of the proposed method.

https://ir.nctu.edu.tw:443/bitstream/11536/29059/1/000174474700001.pdf

A new method for extracting primitives of regular textures based on wavelet transform

Computer graphics: A keyword-indexed bibliography for the years 1976, 1977, and 1978

Traditional approaches for texture segmentation via wavelet transform usually adopt textural features to achieve segmentation purposes. However, for a natural image, the characteristics of the pixels in a texture region are not similar everywhere from a global viewpoint, and over-segmentation often occurs. To deal with this issue, an unsupervised texture segmentation method based on determining the interior of texture regions is proposed. The key idea of the proposed method is that if the pixels of the input image can be classified into interior pixels (pixels within a texture region) and boundary ones, then the segmentation can be achieved by applying region growing on the interior pixels and reclassifying boundary pixels. Based on the fact that each pixel P within a texture region will have similar characteristics with its neighbors, after applying wavelet transform, pixel P will have similar response with its neighbors in each transformed subimage. Thus, by applying a multilevel thresholding technique to segment each subimage into several regions, pixel P and its neighbors will be assigned to the same region in most subimages. Based on these segmented results, an interior pixels finding algorithm is then provided to find all interior pixels of textural regions. The algorithm considers a pixel which is in the same region as its neighbors in most subimages as an interior pixel. The effectiveness of this method is proved by successfully segmenting natural texture images and comparing with other methods.

https://ir.nctu.edu.tw:443/bitstream/11536/29236/1/000173461000002.pdf

Unsupervised texture segmentation by determining the interior of texture regions based on wavelet transform

The U.S. Department of Energy National Uranium Resource Evaluation Program is collecting stream sediment samples at a nominal density of one per 13 km2 from two-degree quadrangles throughout the United States. Each sample has been analyzed for from 14 to 43 chemical elements and other variables. We describe new methods of statistical map analysis, which we have applied to the regional distribution of multielement data from four two-degree quandrangles in the southeastern United States including parts of the southern Appalachian Mountains and the Coastal Plain, with particular reference to uranium distributions. Patterns of uranium distribution are clearly related to the geological provinces and also to individual geologic belts, plutons, and smaller stratigraphic subdivisions. Our work developed several anomalies, some of which were followed up by additional field sampling in 1979 and 1980.

Statistical map analysis techniques applied to regional distribution of uranium in stream sediment samples from the southeastern United States for the National Uranium Resource Evaluation Program

Wir stellen ein Projekt vor, das zur Entwicklung und vor allem zur Implementierung von Renderingverfahren fur realistische Bilder dient. Die Ziele dieses Projekts sind: 


Die Optimierung der Rechenzeiten.


Die Verbesserung der Benutzerschnittstellen fur so ein System.


Die Verbesserung der Bildqualitat, d.h. Verbesserung der geometrischen und optischen Modelle im Rechner.



In diesem System wurden sowohl Ray-Tracing [WHIT80], Distributed Ray-Tracing [COOK84] als auch Radiosity Techniken [GREE86] implementiert. Das Hauptaugenmerk wurde auf die Ausbaubarkeit und die Modularitat gelegt. Wir zeigen, wie eine Aufteilung so eines Systems aussehen kann und wie die einzelnen Probleme in den jeweiligen Schritten gelost werden konnen.

C.H. Hertz

Papers

The ink jet plotter: a computer peripheral for producing hard copy color imagery