GIF Rasterizer Writer Parameters

Image Size

Specifies the image width in pixels.

Note   When the Force Square Pixels box is selected, the width of the output image may not necessarily be equal to the width specified in this field, as the number of pixels will be modified to make each pixel cover a square area in ground units. This adjustment occurs when the aspect ratio of the desired GIF does not match the aspect ratio of the input data’s bounding box.

Specifies the image height in pixels.

Note  As with the Width parameter, when the Force Square Pixels box is selected, the height of the output image may not necessarily be equal to the height specified in this field.

Raster Parameters

Select this checkbox to force square pixels. The aspect ratio of the input data is preserved, but some of the output image may be unused.

To stretch the data to fill the image, clear the checkbox.

Advanced

Raster Extents

Fixes the area that the GIF image will cover in ground units. If not specified, the GIF covers the minimum bounding rectangle of the feature data. If necessary, the ground coverage is adjusted, not the size of the image in pixels, to maintain squareness of pixels. For this reason, the aspect ratio of these settings must be the same as the aspect ratio of Width and Height to ensure that the image provides exactly the desired coverage.

Image Parameters

The color index of the image background. If not specified, Background Image must be specified.

The GIF file to use as the background for the produced image. Lines, polygons, text, and points are drawn on top of this image. If the image is smaller than the size of the output GIF, it is tiled to fill the output image. If not specified, Background Color must be specified.

The transparent color index of the image. Applications that interpret this setting will show the background through any pixels with this color when the image is displayed.

Whether or not the created GIF will be interlaced.

Interlacing is used most often in web applications, as an interlaced GIF gives the illusion of displaying quicker than a non-interlaced GIF.

Whether rows or columns of pixels in the image that are not in the ground range of the feature data should be trimmed out of the image. This setting is ignored when square pixels are not forced. If No, any unused rows or columns of pixels remain blank in the output image.

This percentage value between 0 and 100 controls how much of a border the generated GIF will have. The size of the border is measured as a percentage of the image size. This is typically used to allow annotation at the edge of the scene that would otherwise be clipped to spill into a border around the image. If Trim Unused Pixels is Yes, the border is added after any unused pixels are trimmed.

If Yes, the writer considers the bounds of text when it scales the input features.

Image Map Parameters

The file that will hold the HTML code for the generated client-side image map that can be used in conjunction with the produced GIF to produce a clickable image. If not specified, no image map is produced.

After the translation completes, the file will contain the HTML code for an image map corresponding to the created image. The image map will contain entries for point, line, and polygon features that had a gif_href attribute. Polygons will appear only if they had an area greater than the Image Map Minimum Area, and lines will appear only if they had a length greater than the Image Map Minimum Line Length. Points and lines are buffered by a specified number of pixels to form polygons within the image map, but not within the actual image.

An example image map would look like this:

<MAP NAME="MAPPER">
<AREA HREF="javascript:alert('Trapline\nTRAPLINENO: 2339')" ALT="Trapline - 2339" SHAPE="POLY" COORDS="387,291,386,291,385,291,384,290,383,290,379,288,379,287,371,286,370,286,370,287,369,287,369,286,366,286,365,285,364,285,364,284,363,284,362,283,362,284,362,299,363,303,367,303,367,307,380,307,380,315,388,315,388,319,397,319,397,323,439,322,437,272,412,273,413,288,412,288,411,288,411,289,410,288,409,289,408,289,407,289,406,289,405,289,405,288,404,288,402,287,401,287,401,286,400,286,400,287,397,288,396,288,395,288,395,289,394,289,394,290,393,290,393,289,392,289,388,291">
<AREA HREF="javascript:alert('Significant Site\nSITE: PRINCE OF WALES ARMOURIES Edmonton \nHRV: Provincial Historic Resource')" ALT="Significant Site" SHAPE="POLY" COORDS="169,271,169,279,177,279,177,270">
</MAP>

A web page that included this HTML would also include the generated GIF with a line like this:

<IMG SRC="results20k.gif" ALT="[Query Results]" USEMAP="#MAPPER" BORDER=0 >

The points, lines, and polygons are arranged in the image map such that all lines lie on top of all polygons, and all points lie on top of all lines. This prevents points being obscured by lines or polygons, and prevents lines from being obscured by polygons.

The name of the image map, if one is created. The default is IMAGEMAP. This name will be used in a web page.

The minimum area a polygon must have before it will have an entry in the image map. Features with areas less than this will not have any entries in the image map. The default is 0.

The minimum length a line must have, in ground units, before it will have an entry in the image map. Features that are shorter than this setting will not have entries in the image map. The default is 0.

Lines and points are entered into the image map by computing a buffer around the line, and inserting the resulting polygon. This value controls the amount of buffering applied to the line and points, measured in pixels. The default is 2.

Polygons are generalized before being entered into the image map in order to reduce the size of the image map.

This value specifies the tolerance (in pixels) for this generalization operation. Note that a tolerance of 0 means only collinear points are removed, and the image map should match the input polygon exactly. The default value is 2.