lvmapdlg(3)

LIBRARY ROUTINE
lvmapdlg - Change the map of an image imported from DLG data to displayable colors.

LIBRARY CALL
#include "vinclude.h"
int
lvmapdlg (img)
struct xvimage **img;

INPUT

    1. img -- double pointer to the input xvimage structure.

    The input image and location data will be copied to the output image, but the header and the maps will be lost, so be careful not to overwrite important data.

OUTPUT

    1. img -- double pointer to the input xvimage structure, which now points to the output structure.

    This function returns 1 on success and 0 on failure.

MODIFICATIONS

DESCRIPTION
lvmapdlg is used to convert the maps of a viff image created using dlg2viff from actual geographical attributes to an rgb map of displayable colors. When dlg2viff is used to import digital line graph data, the image created is a multiband bit image. Each band in the image corresponds to a single attribute, or feature in the dlg data. For instance, one band might be for divided highways, another band for two-lane highways, and so on. The map for each band contains the dlg attributes for that band. See your dlg user's guide for a list of attributes. Vmapdlg changes the map from the dlg attributes to displayable colors. For instance, all hydrological attributes will be converted to varying shades of blue.

The map on each band of the input image is expected to be 1 row by 2 columns and use storage type short. The entry will contain two short integers which are the major and minor dlg attributes for the data in this band. The map placed on each band of the output image will be 2 rows by 3 columns, and will use storage type byte. The entries in the first row of each map will be (0,0,0) because we want to assign black as the color for pixels of no data. The other entry will be the rgb triple that represents the attribute in this band.

Here is a list of which categories will be mapped to which colors. The definitions of these colors may be found in the color table /usr/lib/X11/rgb.txt. Only the major attribute is used in assigning a color to a feature. For instance, all attribute pairs with a major attribute in the range 50-59 will be considered hydrography and colored blue accordingly.

    hypsography brown
    streams blue 2
    water bodies blue 3
    hydrography blue 1
    coastal features blue 4
    surface cover green
    non-vegatative surface features cyan
    boundaries grey
    roads and trails red
    railroads tan
    water navigation azure 1
    pipelines and transmission lines yellow
    other significant manmade structures magenta
    survey control markers orange
    US public land survey system pink
    all other categories white

SEE ALSO
vmapdlg(1), intro(3), vipl(3), verror(3), vutils(3) ldlg2viff(3), lvlayer(3)

RESTRICTIONS
The only restrictions on lvmapdlg are on the map type of the input image. There must be one map per band (VFF_MS_ONEPERBAND), the map storage type must be short (VFF_MAPTYP_2_BYTE), the number of rows in each map must be 1 (map_col_size=1), and the number of columns must be 2 (map_row_size=2). It is also required that there only be one image in the input viff file.

AUTHOR
Per Lysne

COPYRIGHT
Copyright 1991, University of New Mexico. All rights reserved.