Raster graphics

As the graphical capabilities of the computer systems became more powerful simultaneously the number of visualized structures increased. With the introduction of raster graphics (1974) and colored raster graphics displays (1979), other forms of molecular representations were possible [197]. CPK models could be represented and colored bonds or molecular surfaces could be visualized. 

The problems with these standards is that they are still years away. Thus packages that state that they are CORE "compatible" rather them fully CORE compliant or compliant to a particular level - exist because the CORE is a moving target, that movement being forced by a need for completeness and rapidly changing technology (the 1979 specification has raster graphics as an appendix - it is now an major consideration). 

Connolly (43,44) and Richmond (45) also developed analytical methods for calculating molecular surface area and volume, which provide nearly exact values for the surface area and enclosed volume. Richmond s method provides analytical derivatives for surface area with respect to the cartesian coordinates of the atoms, which may be useful for docking (Section V). Connolly s algorithm also produces spectacular shaded raster graphics images (46), which give a very different feel for a macromolecular surface than conventional space-filling displays. 

Raster Graphics Digital images that use pixels arranged in a grid formation to represent an... 

Figure 5 A CPK-style model displayed on a raster graphics system, circa 1979...

The first graphical representation using MATLAB software is that of a two-dimensional contour surface plot of the data from Table 75-1 [2], This Figure 75-3 plot can represent multiple levels of j-axis data (absorbance) by the use of contours and color schemes. The MATLAB commands for generating this image are given in Table 75-2 where A represents the raster data matrix shown in Table 75-1. 

At the same time, the power and capabilities of standard PCs increased dramatically. The Richardsons (Richardson and Richardson, 1992) at Duke University developed molecular graphics programs to run on the Macintosh. In a dramatic development, the World Wide Web emerged. Roger Sayle created RasMol as part of his PhD dissertation at Oxford, and made the source code freely available on the web. This program allowed raster display of molecules on UNIX or PCs. The RasMol... 

Merrit EM, M RASTER 3D version 2.0 a program for photorealistic molecular graphics. Acta Crystallogr 1994 D50 869-873. 

The results and their interpretation are comparable with other published results (for instance [HOPKE et al., 1976 VAN ESPEN and ADAMS, 1983 KEIDING et al., 1986 VONG, 1993]), but this is only a plausible explanation of a mathematical hypothesis. The graphical representation of the computed factor scores can verify this hypothesis. As demonstrated in the literature [EINAX and DANZER, 1989], representation of the scores of the main factors enables complete territorial separation of the investigated emission impact monitoring raster screens but only a relatively fuzzy temporal separation. 

The first method [87,88] uses a matrix form of the Beer-Lambert absorption law in a transmission mode. A 2-D material sample is raster-scanned by a pulsed, tunable THz source to generate an N rows x L columns image matrix [/] where N is the number of THz frequencies used and L is the number of pixels. The values of [/] are the measured total absorbance at each pixel. Separate absorption experiments with known materials of interest establish the THz spectra both graphically and through the N x M spectra matrix [S], where M is the number of components. The collection of species can include non-agent materials that can affect the absorptions for example, barrier materials with spectra that are typically weakly frequency dependent. The spatial patterns of the agents are contained in the M x L matrix [P], The values of [P] effectively contain agent concentration information. 

Raster technology provides a different approach to CRT graphics. Raster devices have one thing in common with vector refresh displays - they must be updated 60 times a second. But rather than moving a beam between... 

With both vector and raster technologies, there are also the questions of tightly couples vs loosely coupled devices and graphics protocols. 

There are three Tektronix terminals that are emulated, the 4010, 4014 and 4027. The 4010 is a high resolution terminal with cross hair cursors for graphics input, the 4014 adds a hardware line patterns, choice of character sizes and user definable character sets with local storage for commonly used structures. The 4027 is a color raster terminal with 64 colors, 16 character fonts, as well as polygon and vector commands. 

Tel. 206-543-1421, fax 206-543-1524, e-mail merritt xray.bchem.washington.edu Raster rendering of proteins and other molecules in stick, ball-and-stick, spacefilling, and ribbon representations. Available via anonymous ftp from stanzi.bchem.washington.edu (128.95.12.38). Silicon Graphics and Sun. 

Merritt EA, Bacon DJ. Raster 3D photorealistic molecular graphics. Meth. Enzymol. 1997 277 505-524. 

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