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Wasmer Consulting - BaseOps - User's Guide - Exporting Maps as Bitmap Images


BaseOps User's Guide, Chapter 35: Exporting Maps as Bitmap Images

Using BaseOps, you can create a bitmap image of a map. The image can be stored in a file or copied onto the clipboard. More than a mere screen capture, the image can be created at a high resolution (for example, 600 pixels per inch), resulting in a publication-quality image. For low-resolution maps that will be displayed on a computer monitor, you can use oversampling to improve the map's appearance.

Exporting a Map to a Bitmap Image File

To export a map to a bitmap image file, choose Export Map to Bitmap from the File menu. The Bitmap File Export Options dialog box appears.

The Bitmap File Export Options dialog box is a Multiple Page dialog box. See Multiple Page Dialog Boxes for more information.

Copying a Map to the Clipboard

To copy a bitmap image of a map onto the clipboard, first ensure that the map has the keyboard focus by pressing Alt + M, then either choose Copy from the Edit menu, or press Ctrl + C. The Clipboard Copy Options dialog box appears. This dialog box is identical to the Bitmap File Export Options dialog box, with the exception that the page used to specify the destination file and format is not present.

In this chapter, only the Bitmap File Export Options dialog box will be discussed. Keep in mind, however, that the options described also apply when a map is copied to the clipboard.

Destination File Name and Format

Use the File page of the Bitmap File Export Options dialog box to set the name and format of the file where the bitmap image is written.

In the box provided, type the name of file where the bitmap image will be written. Press the Browse button , located to the right of the text box, to display the Open File dialog box, which allows you to browse for the file.

Select the image format of the file. You have the following choices.

JPEG Options

If you select the JPEG format, the Options button will be available. Press it to display the JPEG Options dialog box.

Type the image quality number, an integer between 1 and 100. The Image Quality number controls the tradeoff between compression and image quality in JPEG images. A value of 100 produces the highest quality image, but also results in the largest file size. Conversely, a value of 1 produces the smallest file size, but also results in a severely degraded image.

Selecting an Image Format

The JPEG format is intended for storing photographs. Most maps are line images, so one of the other image formats will usually be a better choice. However, if your map has areas of smoothly-changing color (for example, a map with an aerial photograph for the background), JPEG will be the best format.

Neither the BMP nor the TIFF formats are compressed, so they will produce large files. However, both are very common formats. The BMP format, in particular, is very well supported on the Microsoft Windows platform. If you intend to import your image into another program, the BMP format is an excellent choice.

If you intend to archive the image, or display it on the web, the PNG format is a good choice. It achieves high compression on most maps. It is a newer format than the others, but most applications (and in particular, most web browsers) now support it.

Image Size

Use the Image Size page of the Bitmap File Export Options dialog box to select the size, resolution, and color depth of the bitmap image you will export your map to.

Image Color Depth

Select the color depth of the bitmap image. This is the maximum number of colors in the bitmap. You have the following choices.

Image Size

Select the method used to specify the dimensions of the bitmap image (i.e., the width and height of the bitmap, in pixels) that your map will be exported to. You have two choices.

Caution:

Your computer's memory limits the maximum size and color depth of an export bitmap image. If your computer takes an exceptionally long time to export a map to a bitmap, you may not have enough memory. This is especially true if your hard drive light stays on constantly while creating the image. Try reducing the image's size and/or color depth.

The image's resolution does not affect the amount of memory used.

Image Resolution

The resolution of a bitmap measures the size of the pixels. It is typically expressed in pixels per inch or pixels per centimeter.

As an example, assume that your map has features that are drawn with 1-millimeter-wide lines. If you export this map to a bitmap image with a resolution of 100 pixels per centimeter, these lines will be 10 pixels wide.

Computer monitors typically have a resolution of 70 to 90 pixels per inch. Laser printers typically have a resolution of 600 to 1200 pixels per inch.

Select the method used to specify the image resolution. You have two choices.

Oversampling

BaseOps can use oversampling to improve the appearance of low-resolution maps. Oversampling reduces jagged edges. In technical terms, it antialiases your entire map.

The amount of oversampling is controlled by the oversampling factor, an integer between one and eight. An oversampling factor of one means that oversampling is not performed. Higher factors result in smoother, higher-quality images, but also dramatically increase the amount of memory required to export a map.

Use the Oversampling page of the Bitmap File Export Options dialog box to set the oversampling factor used when exporting a map to a bitmap image.

Type the oversampling factor in the box provided.

When using oversampling, you should choose 24-bit true color or 8-bit grayscale color for your image. See Image Color Depth.

Caution:

Oversampling dramatically increases the amount of memory needed to export a map to a bitmap image. The amount of memory required is proportional to the square of the oversampling factor.

Until you gain familiarity with your computer's capabilities, it is recommended that you initially export your map with a low oversampling factor, and then attempt to export it with gradually increasing factors. If your computer takes an exceptionally long time to export a map, you may not have enough memory. This is especially true if your hard drive light stays on constantly while exporting. Try reducing the oversampling factor.

Area to Draw

Use the Area To Draw page of the Bitmap File Export Options dialog box to select the portion of your map that is drawn on the exported bitmap image.

Select the area to draw. You have two choices.

Note:

If the Area to Draw is not the same shape as the export bitmap image (i.e., if the aspect ratios are different), the area drawn will be larger that the area requested.

Note:

If you export a map to scale, BaseOps attempts to display the Area To Draw at the requested scale. If the requested scale is too large, this area will not fit on the bitmap image. In this case, you have four options: 1) choose a smaller scale, 2) choose a smaller Area To Draw, 3) increase the size of the bitmap image, or 4) decrease the resolution of the bitmap image.

Scale

Use the Scale page of the Bitmap File Export Options dialog box to set the scale at which your map is drawn on the export bitmap image.

Select how the scale is determined.

Level of Detail

Use the Level Of Detail page of the Bitmap File Export Options dialog box to control how much background map detail is displayed when you export your map as a bitmap image.

Many background maps specify a minimum scale at which various features should be displayed. As you zoom in on such a map, additional detail is displayed. The intent is to prevent excessive detail from cluttering a map when it is displayed at a small scale. See Background Map Formats.

Use the Level of Detail page to control how BaseOps uses this recommended scale information when you export your map as a bitmap image. You have four choices for how BaseOps determines how much detail to display.


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