The paper basemap selected for scanning and vectorization for the pilot exercise was a color topological map at a scale of 1:25,000. Please select a map that you would like to vectorize and follow the process detailed below using your preferred scanning software. After you have saved the image in JPEG (compressed) or TIFF file format, you should continue on to Exercise 1B to learn a vectorizing protocol.

Adjusting Scan Settings

The software scan settings discussed below were adjusted for the size of the original basemap and to enhance to quality of the scan.  Many of the contour lines were very tightly drawn on the paper basemap and tended to bleed together and we wanted to delete the roads and airport features from the scanned image by separating out the unique color they were printed in.

To begin scanning a basemap, you must first input the width of the basemap area to be scanned. Most software programs allow you to select a scan area in terms of American National Standards Institute (ANSI) units, International Standards Organization (ISO) units or in scanner units unique to the scanner you are using.

· If you select ANSI units, you must choose between standard paper format sizes labeled A, B, C, D or E. For example, if you want to scan an 8 1/2x11" page, you select ANSI A. B is for an 11x17" page. C is for a 17x22" page. D is for a 22x34" page. E is for a 34x44" page. F is for a 28x40" page.

· ISO units, like ANSI units, are pre-selected scan sizes.  They are measured in metric units.

· Finally, if you select Scanner Units, you must measure your basemap width using the scanner units ruler printed on the scanner. The scale on the Ideal scanner runs from 0 to 8.5 units.

Secondly, you must adjust your software scanning program settings for light threshold, resolution, index color, brightness and contrast.

(For Grayscale/Black and White Scans)

Scanning software will offer a range of values, such as 200. The maximum threshold value selected determines the amount of light the scanner emits. The higher the threshold value selected, the fainter the lines on the scan. If set too high, the lines will break up and vectorizing becomes problematic.

(For Grayscale/Black and White Scans)

For the system used in this exercise, the maximum hardware scanning resolution is 400 dots per inch (dpi). The WIDEImage scanning software used in this course allows an interpolated maximum scanning resolution of 800 dpi. Resolutions of greater than 400 dpi are achieved through the software’s ability to create data values at a density greater than 400 dpi, at a max of 800 dpi. This density is possible through an interpretation algorithm that generates values for all pixels falling between the actual hardware scanned pixel values. Through interpolation we achieve a scanned resolution of 600 dpi for the basemap in this example.

(For Color Scans Only)

The maximum number of index colors possible is 256. We recommend that when scanning a color map you select a maximum index color value equal to the number of colors in the basemap able to be separated with the naked eye.

(For Color Scans Only)

The appropriate brightness setting may vary with the quality and medium of the image being scanned, however, often a median value, such as 50 on a scale of 1 to 100, will work best.

(For Color Scans Only)

Selecting an intermediary value on a scale of 1 to 100 is probably optimal. However, if scanning an image of little grayscale or color contrast, a high value setting may yield a better result.

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