How to create a map picture

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How to create a map picture

 

Things to know first

Picture size

Picture size is equal to the elevation matrix pixel size defined in Map properties. It has a direct impact on program performance. The amount of calculation increases by the square of picture side, as well as the memory needed. First try small pictures (400x400) to test your machine.

Video settings

The best compromise is definitively 16-bit colour setting (65536 colours). Some function gives poor results at 8 bits colour setting (256 colours).

Draw mode

Each mode can be used to enhance terrain characteristics. The most common draw mode is Grey scaled slope, because networks features are better seen.

 

About Picture properties

Grey scaled slope

This option is used to draw the topographic map using a gray colour scale according to the terrain slope. In this mode, the map is drawn as if lighted from the azimuth entered in the Light Azimuth entry box, such that slopes facing the direction of the light source are the lightest, and slopes facing away from the light source are darker. Horizontal terrain is drawn with the average colour shade given by the Brightness entry box. The range from lightest to darkest shade is prescribed by means of the Contrast entry box.

Coloured slope (absolute)

This option is similar to the Gray scaled slope option with the exception of the colour. In this mode, the colour is related to the elevation (h) above sea level according to the following scale:

 

Elevation range Colour

h < 0m             Magenta

0m <= h < 100m     Cyan

100m <= h < 300m   Green

300m <= h < 700m   Yellow

700m <= h < 1500m  Orange

h >= 1500m         Gray

 

Coloured slope (relative)

This option is similar to the Coloured slope (absolute) option with the exception of the elevation range. The colours are the same, but they are scaled to the Bottom elevation and Top elevation entries.

X-ray

This option is used to draw the topographic map using a gray scale. In this mode, the map is drawn in relation to elevation, with the highest points the darkest and the lowest points the lightest. The gray scale is relative to the Bottom elevation and Top elevation entries.

X-ray (inverted)

This option is similar to X-ray, but with the highest points the lightest and the lowest points the darkest.

Rainbow

This option combines shadows with a user-defined colour in order to produce a million colours picture if the video mode enables it. Activate the Colours button to open the Colour edit form.

Bottom elevation

Minimum elevation threshold in meters.

Top elevation

Maximum elevation threshold in meters.

Contrast

Percentage of contrast.

Brightness

Percentage of brightness.

Light Azimuth

Azimuth in degrees from which an imaginary light source illuminates the terrain.

10 meter contour intervals

This option generates darker contour curves at every 10m of elevation.

100 meter contour intervals

This option generates darker contour curves at every 100m of elevation.

500 meter contour intervals

This option generates darker contour curves at every 500m of elevation.

Draw objects

This option will exhibit roads, lakes, boundaries and labels defined in .plt files (OziExplorer format) located

in a sub directory object if they are within the map limits.

Show cities

This option will exhibit cities defined in file cities.dat if they are within the map limits. If selected, Font and

back style can be selected with the Font button and Transparent checkbox.

 

Step-by-step

1. In File menu, select New picture.

2. Select Grey scaled slope, 30% contrast, 70% brightness, 335 deg. Light azimuth, no Cities, and no Contours.

3. Click on the Apply button.

 

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23rd January 2014