MapGuide maps presented on the
MapPlace may be viewed at virtually any scale. These maps may be printed
to any desired scale using MapGuide’s ‘Printer Setup’ and
‘Print’ functions available through the Pop-up Menu. MapGuide also
allows the map window of a MapPlace view to be copied to the clipboard and
from there into any number of other Windows programs such as PowerPoint
and Word (secondary programs). Unfortunately, during this process the
scale of the image is not preserved. This note describes the reasons for
this lack of scale passing and a procedure for correcting the scale of a
map after the Copy & Paste process.
The ability to Copy & Paste a map
from a MapPlace view into another software package has proven to be a very
popular feature. Map objects such as symbols, lines and polygons may be
ungrouped and individually modified or deleted in many secondary programs.
Often a map at an exact scale is not necessary but on occasion it is
essential. Some simple measurements, calculations and edit procedures are
required to restore an accurate scale to the map drawing in the secondary
program.
The actual shape of a map on a
computer screen is dependent on the screen resolution settings and the
associated aspect ratio. The combination of screen viewing dimensions and
the horizontal and vertical pixel settings affect the proportions of all
objects viewed on the screen (Figure 1). MapGuide’s functions such as
‘measure distance’ and print related functions can detect the required
screen values, desired scale and the resolution of the output device to
generate an accurate distance measure or hardcopy output at a required
scale. But, during the Copy & Paste process all map objects are
referenced to the screen coordinate system and there is no prior knowledge
of the output device (secondary program). Therefore the required scaling
cannot be automatically performed.
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Figure 1. Monitor settings of
1280 X 1024 and 1280 X 800 resulting is aspect ratios of 1.25 and
1.66 respectively. The map on the right is stretched in a N-S
direction and these proportions are carried to the secondary program
after the Copy & Paste (Figure 2). |
A five step procedure may be used to
transfer the map objects from a MapPlace view to a secondary program and
adjust the map to a desired scale.
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Obtain the best view possible of
the map to be captured. The best quality end product is obtained by
capturing the most detail possible from the MapPlace window. To do
this one should zoom in as close as possible to the area of interest
and set the monitor pixel values as large as permitted by the
system.
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Measure the ground distance
between two map objects in an E-W and N-S direction. A map grid is
very useful for this purpose and can be removed after ungrouping in
the secondary program if desired. Use the MapGuide ‘View
Distance’ tool in the Pop-Up menu for this purpose. The
measurements must be in a N-S and E-W direction and not on a
diagonal. Record these distances for use in the following
calculation step.
-
Calculate the map distance
between these two pairs of map features to obtain the desired scale.
The required calculations are very simple. Once the desired scale
has been determined, say 1:1,000,000, the required map distance
between the two pairs of measured map features from step 2 can be
determined. For example two features 50 km apart on the ground must
be 5 cm apart on the map for a scale of 1:1,000,000.
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‘Copy & Paste’ the map
window into the secondary software. Use the MapGuide ‘Copy’
button on the toolbar or the ‘Copy’ feature in the Pop-Up menu
to copy the map window. Then move to the secondary program and
‘Paste’ the map. Prior to pasting-in the map make sure that the
output format of the secondary program is set to the ultimate output
page size.
-
Adjust the distance between the
two map objects to get desired scale. Most software that will be
used to receive a MapPlace ‘Copy & Paste’ map will have an
option to turn on rulers which can be used to measure distance on
the pasted map. Once the map has been pasted into the secondary
software it should be cropped as much as possible. Then the whole
image can be stretched or compressed in an E-W and N-S direction so
that the distances between the two pairs of measured map features
are the required map distance apart (Figure 2). Once the scale has
been set the image can be ungrouped and any modifications performed.
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Figure 2. The left image
illustrates the shape of the pasted map immediately after it is
pasted into PowerPoint after being copied from a monitor with pixel
settings of 1280 X 800. The right image shows the map after the
pasted image was cropped and stretched horizontally and vertically
so the measured map features were the desired distance apart. Note
the rulers along the upper and left side of the image. |
Notes by Ward Kilby, April 15,
2004 as part of a BC Yukon Chamber of Mines 2003
funded 'Rocks to Riches' program
to develop MapPlace
Client-mapping Tools.
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