The Surface Definition tools are used to define and edit the landscape
surface. Unlike in many terrain programs, GenesisIV has the concept of
an undefined height, which is useful when manipulating heights. Terrain
Definition Tools are used with the height layer. To activate you must
have this layer selected from the drop down list. The Surface Tools are:
Spot Height |
The Spot height tool displays the height of the selected
grid point. Enter either null or a new height value. Note that you
can set all heights to null by selecting 'Clear All to Undefined'
from the Edit menu.
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Default Height |
Similar to the Spot height tool. If entering several points at the
same height the Default height tool can be used to set each grid point
to the last height entered with the spot height tool.
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Manual Contour Trace |
The Manual contour trace tool is used to set a series of sample
points along a line to be set to the same height. Typically this tool
would be used to trace the contour lines on a bitmap loaded as background.
The tool uses a combination of the left and right mouse buttons or
clicks and double clicks. To start a contour press the left mouse
button. You may now either move the mouse whilst holding down the
button, or release the button and click again at another position.
In both cases a red line highlights where the contour will be placed.
Continue defining the contour using any combination of these actions
until complete, then either double click the left button or click
the right button. A dialog box prompts for the height of the contour.
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 Auto
Contour Trace |
The Auto-contour trace tool is also used to set a series of sample
points along a line to be set to the same height. It traces the contour
lines on a bitmap loaded as background, and behaves in a similar manner
to the Manual contour trace. Your background bitmap must be black
or colour detail on a white background. The auto-contour tool works
by following a selected line. It is colour-sensitive, and give best
results on scanned image if they are 'cleaned up' using a paint package
an/or the Map Filter utility before use.
To start tracing a contour press the left mouse button over a contour
line. The program will now proceed to follow the line over the image,
reversing the line colour as it does so. On completion a dialog
box prompts for the height of the contour. By default, the trace
only follows pixels of exactly the same colour, however when using
the tool to trace contours from background bitmaps with 256 colors
or more you may find it useful to widen the range of colors recognized
as belonging to the same contour. To do this use the color tolerance
slider on the map page of the parameters notebook.
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 Level
Heights Block |
Blocks of grid points may be set to the same height using the Area
heights tool. Click and drag using the left mouse button to define
a rectangular area. On release a dialog prompts for a height (or null)
to which all sample points within the area will be set. Note that
you can quickly set all heights to null by selecting 'Clear All to
Undefined' from the Edit menu.
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 Mask
Height Block |
This tool is used to make complex adjustments to a heightfield.
Click and drag the tool over the landscape to draw a mask - shown
as a grey/black darkened area. When satisfied right click to bring
up the Set Height dialog. The area can be set to an exact height or
undefined, in which case all points will be set to the same height,
or a value added/subtracted, for which the height applied will be
modulated by the denisty of the mask.
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Interpolation |
The Interpolate heights tool is used to interpolate the heights
of undefined (null) grid points, and would typically be used after
defining a representative sample of points. Interpolation is one of
the most powerful features of GenesisIV and is discussed in more detail
separately. |
Water Definition. This single tool works with the heights layer, to activate
you must have this layer selected from the drop-down list.
Flood Height Height |
The Flood tool flood fills any flat area of the map
with water. After defining the shape of your landscape click on a
suitable terrain square. If the four bounding sample points define
a flat square a dialog will prompt for confirmation that all contiguous
flat terrain squares at the same height are to be set to water.
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Terrain Definition Tools are used with a Surface, Vegetation or Model terrain
layer. To activate you must have an appropriate layer selected from the
drop down list.
Select Vertex |
Terrain polygons are displayed on the landscape as hatched
polygons. Using the Select terrain item tool any polygon or line vertex,
or a model point may be selected and moved by dragging. Right-click
the mouse to display the polygon pop-up menu - this allows you to
insert or delete a vertex, delete the selected polygon, or delete
all polygons for the current layer. Similarly selecting a model point
enables the model pop-up menu - this allows you to edit the model
parameters, delete this model or delete all models in the current
layer.
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 Add
Line |
Similar to the Spot height tool. If entering several points at the
same height the Default height tool can be used to set each grid point
to the last height entered with the spot height tool.
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Add Terrain Area |
The Add terrain area tool allows you to manually add a polygon.
Successive clicks on the map canvas defines additional points. To
close a polygon right click.
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 Add
Model |
The Add model at point tools allows you to add a model at any point
on the landscape. Click on the map to place a new model - a dialog
box appears that allows you to override the default height and rotation
parameters for the model defined for the current layer. |
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