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SurView TutorialDisplay attributes |
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Because of the diverse nature of the types of data and data files that SurView deals with, there are three distinct ways to access the display attributes for the files:
![]() legend window |
Use the Edit | Display attributes... dialog box to access
the fixed attributes (those that are specified as constants and
are not derived from a lookup table).
Use the Edit | Display attributes... dialog box to access
the display attributes of these files. Selecting an item will bring
up other dialog boxes, including the 'fixed attribute' dialog box
for ASX (SHP) files.
Selecting Edit | Display attributes... brings up a dialog box
that provides access to the display attributes of each file. Some files
have more than one set of attributes, each with its own dialog box.
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There are several attributes that are specific to SLD files:
In addition, SLD uses the same attributes used by BOB files to draw variable-size scaled dot maps (colour, style, scale factors).
SLD display attributes are discussed in greater detail on the SLD page.
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For 2 & 3-variable composite images, there are no display attributes - the files are assumed to contain RGB or CMY colour values ready to display.
For single-variable grids, there are two basic entities that control the appearance of the grid:
The palette file & optional remap table is specified in the GRX file that serves as a wrapper around the grid file. There is a single dialog box to manage the use of these files.
![]() initial display |
Step 1
The initial display shows the colour table as a series of parallel
bars of equal height. This example uses an 89-colour palette. The
associated data values for the current remap table can be seen by
moving the cursor along the base of the colour table display. If
the GRX file was not set up with an external remap file, the [min,max]
range (read from the GRX file) is divided into N equal intervals,
where N is the no. of colours in the current palette. This represents
a linear remap table. In this example, the overall data range is [-0.08,9.82].
![]() histogram for [-0.08,9.82] |
Step 2
A histogram of the data distribution can be accumulated by
entering the desired [min,max] values and clicking New.
After the histogram has been accumulated, the heights of the colour
bars represent the amount of each colour. Note that this does NOT
change the remap table. In the example, it is clear that although
the absolute [min,max] of the data is [-0.08,9.82], the values
above ~3 are spurious values.
![]() histogram for [0,3] & new levels |
Step 3
With this knowledge in hand, the histogram is recreated using a
range of [0,3] to eliminate the spurious values. This in itself
will not change the display. Then the Range option is
used to specify that the range [0,3] should be divided equally into 89
colours. The histogram now shows a good distribution of colours.
The Range option can also be used to specify:
The Interval option can be used to specify:
The Individual option can be used to view
and/or edit the individual colours in the remap table.
In addition, a new palette file can be selected. If the no. of colours, does not match the current no. of remap levels, the remap table is discarded and the [min,max] range is divided into N equal intervals, where N is the no. of colours in the new palette.
The remap levels can also be saved in an external file for subsequent re-use.
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Points are displayed from .BOB files, usually created by importing points from a .DBF file. Each .BOB file can contain one of two distinct types of points:
![]() variable-size dot map |
Dot map
A very useful map of data distribution can be created by
changing the symbol type, colours & styles and scaling
the size of the symbol to the data values. This is a common
display method for multivariable geochemical data.
![]() point attributes |
Point attributes
The no. of styles of points in BOB files depends on the
nature of the data. But each style has a set of attributes
(symbol type, line & fill colours, size or scale factors,
rotation angle, etc). While viewing the .BOB file of points,
several of the attributes can be changed and the various
styles can be enabled/disabled. All of the styles can be
changed from a single general-purpose dialog box, except
the scale factors.
![]() point scale factors |
Point scale factors
To edit the scale factors, from the dialog box,
choose Scale (if enabled, for proportional-size dots)
to bring up the dialog box that allows the scale factors to
be edited.
The statistical distribution of the data is shown in the graph, either as a linear or log plot of 'normal quantile' (cumulative probability) versus the data value.
The scaling equation allows a selected [min,max] data range
to be used to scale the symbol in a linear or non-linear
fashion. Values that lie outside the scaling limits can be
hidden or clipped.
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There are two attributes for arcs (polylines):
Arcs (polylines) can be displayed by both .BOB and .SHP files:
If the values are fixed, you can edit them in the 'fixed
attribute' dialog box. If they are drawn from a LUT, right
click on the legend window for the file to access the
attributes - you can edit
the colours and enable/disable the different types of lines.
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There are 3 classes of attributes for polygons:
Polygons can be displayed by both .BOB and .SHP files:
Any of the 3 attributes that are fixed (including 'none') can be edited in the 'fixed attribute' dialog box. If they are drawn from a LUT, locate the legend window for the file and right click on it to access the attributes - you can edit the colours and enable/disable the different types of lines.
Example 1:
A SHP/ASX file of lakes might be set up with:
These are all fixed attributes and can be edited with the 'fixed attribute' dialog box.
Example 2:
A SHP/ASX file of geological units might be set up with:
In this case, only the line attribute can be changed with the 'fixed attribute' dialog box. The other two attributes are accessed by right-clicking on the legend windows (there will be one for 'rock unit' and another for 'age').
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The only way that text can be used to annotate a map is to put the text
into a .BOB file, with appropriate (easting, northing) or (longitude, latitude)
co-ordinates. Each text string is assigned a style (which has an associated
size, rotation angle and colour) when the BOB file is created. While viewing
the .BOB file of text, the colour can be changed and the various styles can
be enabled/disabled.
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