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The image-map settings
· The first controls in the image-map-dialogbox are two switches. The first one toggles the image-map »ON/OFF«, whereas the second switch determines, whether the image should be tiled or projected onto the object just once. · Supposed you have an appropriate image-map, the »tiled«-option enables you to create walls, bricks, tiles for bathrooms and so on very quickly. But the tiled-option has one disadvantage: compared to real 3D-objects, an image-map looks always somewhat »flat«.
Projection type · One thing, you never should forget when working with maps is, that an image is a 2D-sheet, which has to be applied onto a 3D-object. It is therefore neccessary to take the shape of the 3D-object into consideration, when it comes to projection. · POV-Ray offers four kinds of image-projection, that can be selected in POVLABs mapping-dialog. These four options are: A - planar mapping: this mapping is used, when the image is projected onto a box or otherwisely square objects. B - spherical mapping: used, when the image is to be attached onto a sphere-like shape. C - cylindrical mapping: commonly used for cylindrical shapes and D - torus like mapping: assumes, that the 3D-object is a torus (donut, ring ...). |
· Although these options give you great freedom in using image-maps, the bitmap you are using, should at least in some way be suited for the respective kind of projection. Otherwise you will face severe distortions (though this can be used intentionally). The best thing to do is to experiment a bit with the different kinds of projection.
Image-map interpolation · Due to the fact, that image-maps are regular bitmap- graphics, they are consuming considerable harddisk- space (especially when they come in a good quality and resolutions above 150 dpi). In some cases it is therefore neccessary to compromise between image-quality and required diskspace. This is usually done by downscaling the resolution or the size of the image-map. But this - of course - affects the quality. · To achive a good rendering though, you can use one of three methods of »image-interpolation«, which can be applied via POVLABs mapping-dialog. »Interpolation« means, that POV-Ray checks out adjacent pixels in the image-map and genarates a new pixel inbetween, if the difference in color or luminance is too big. The result is a kind of picture which you get, when you use a »soften«- or »blur«-filter in an image-processing application. Normally interpolation is just some sort of »patch« or »bugfix« and should only be used, when the image-map is not too good. In this case the interpolate-feature can satisfyingly improve the result. Applying and altering image-maps · As the last control in the image-map-dialog you will find a button labeled »(no file)«. Click on this control to browse through your map-libraries on your harddisk. You can chosse any file-type that is accepted by POV-Ray. In detail the most common used types are: A - GIF87/89a, B - TGA, C - PNG (portable network graphic-format) and D - SYS, which is a system-specific graphic-format (for instance »BMP« on Windows- or OS/2-machines). Image-libraries · There is one thing you should do first, and that is to specify the paths for your map-libraries. This can be done by clicking on »material« | »libraries«. You will then get a dialogbox, where you can specify up to five library paths (e.g.: »c:\povlab\maps\tiles« etc.). |
| Chapter B/Page 12 | 
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