Axion 3D Atlas/ATLAS.iso/manual/m_3d.txt

Text File | 1998-03-17 | 8KB | 131 lines

{bigtext=20,85,"3D View"}

{4}If you zoom in far enough on the 2D View map of the world, you can clip out
the area showing on screen to view it in 3D View. This lets you view the terrain
in 3D perspective. In order to clip out an area, please zoom in to at least
1:11,000,000 scale. Note that you do not have to clip out an area every time.
You can keep the area that you have previously clipped out (or the sample one
provided on the CD) by answering 'no' to the prompt.

If you are not zoomed in far enough of the 2D map, the program goes back
to a top-level view of the world and gives you a cursor to select where you
want to clip out data. Accept by clicking the left mouse button, or keep the
existing clipped-out data by clicking the right mouse button.

Once you have clipped out an area, the menus along the right-hand side of the
screen will change:

{3}Display Type:{4} Allows you to pick what type of imagery to drape over the
terrain model. You have your choice of:

   {3}Satellite imagery:{4} (same as the default image shown on the 2D view map of the world)
   {3}Aspect:{4} this shows which way a part of the terrain is facing, such as the north
   side of a hill, south, side, etc.
   {3}Slope:{4} this shows how flat the terrain is, from perfectly flat (plateau) to
   completely vertical (cliff). The value is shown as a degrees value like the
   grade of a road, where 0 degrees is flat and 90 degrees is vertical.
   {3}Elevation:{4} Shows the terrain model color coded based on height. The colors are from the
   currently chosen color scale showing at the right side of the screen, scaled from minimum
   height to maximum height.
   {3}Shaded relief:{4} shows the gray shaded relief of the terrain. This shows up
   drainage features, ridges, valleys, and other geological formations well.
   {3}Details:{4} If you had any vector data types turned on when you were back on the
   2D view at the time you clipped out this piece of terrain, then you can overlay
   a coarse version of the same vector data such as roads or international boundaries on
   top of the terrain. The underlying raster will be whatever was showing at the time
   you clipped out the terrain. This overlay type is available only when the terrain
   surface is in high resolution, not medium or low resolution.

{3}Panorama:{4} This function allows you to find out what you could see from a
particular point on the terrain, at a given height before your view was obstructed
from mountains or other features. To start, click on the 'Panorama' button. You will
now see a small window with some controls in it:

   - The circular area at top left lets you set which direction you are
     facing, assuming a 120-degree field of view. use the mouse to drag
     the wedge-shaped area to point in the correct direction.
   - The 4-pointed arrow lets you adjust the viewer location on the surface
     of the ground. Click and hold the mouse on the arrow control, and as
     you drag the mouse you should see a small red crosshair traveling across
     the surface of the large terrain model still showing on the main screen.
     When you reach the location you want, simply let go.
   - You can also adjust at what height you want the observer to be above
     the surface of the terrain by using the scrollbar. It ranges from 2
     meters (to represent a person standing on the ground) to 6000 meters
     (as if you were in an aircraft flying over the ground).

Once you adjust the position to your liking, click on the 'refresh'
button. The large terrain model on the main screen will now redraw,
as the program is calculating what is and is not visible from the
observer location. The field of view cone is shown in red, with the
visible areas within it shown in green. The rest of the terrain is
shown in shades of gray. When it finishes, drawing the terrain model,
a second view will also be drawn at the bottom of the screen. This is
the view from the observer's point of view. It is drawn using the
color satellite imagery data. You can then pick a different point as
many times as you want, or click on the arrow or press ESC to close
the window.

{3}Cross section:{4} This lets you see a cross section or profile of the ground
between any two points on the terrain model. When the little map pops up, click
in two locations on it. You will see a red line drawn between the two chosen
points, and the profile will be shown at the bottom of the screen. You can also
adjust the vertical exaggeration in order to get a better idea of the vertical
scale by using the 4 buttons at the right end of the bottom window. You can keep
choosing other cross-sections, or press ESC to close the window when done.

{3}Names:{4}  When you clipped out the section of terrain from the 2D View map,
any city names within that area were also saved. You can display the locations
of the cities on top of the terrain model by turning on this option. They will
be shown as little flags at the location of the city. Additionally, if back in
the 2D View mode you had searched the database of 1.6 million populated places
to display the location of a specific place on the map, that location will also
show up, but drawn in a different color.

{3}Options:{4} Allows you to pick a different color scale for when you are showing
the elevation data.

{3}Flooding:{4} If you click this button, the terrain model will be shown in shaded
elevation, and you will see a popup window with a color scale and slider bar.
You can then see what would happen if the water level was raised by a certain
amount by interactively dragging the slider on the color scale to adjust the
water level value. Or, you can specify an exact value to flood to (for example,
41 meters above sea level), and hit 'render' to see the result. When done, click
the 'close panel' button or hit ESC. Note that the elevation value that
you type in for the exact value is referenced from sea level, not the minimum
elevation of the section of land you are looking at.

{3}Resolution:{4} Increases or decreases the resolution of the terrain model in
order to adjust the quality. The more points that are displayed, the longer it
takes to draw. There are currently 3 different grid resolutions available
(100x100, 150x150, and 350x350).  The program defaults to medium resolution.
High resolution is best to use if you want to see fine details when using the
'Panorama' function or when you want to print out a nice copy of the terrain on
the printer.

{3}Exaggeration:{4} Increases or decreases the vertical exaggeration of the terrain.


At lower right, there is also a small panel labeled 'Tools' with some controls
in it:

- The 2-pointed arrow at top right allows you to zoom in closer or farther to
  the terrain model. Click on the control, and hold the mouse button down.
  Then drag the mouse up or down in order to adjust the view. Let go, and the
  terrain model will be redrawn at the new location.
- The 4-pointed arrow on the sphere lets you rotate the terrain left or right,
  and tilt up or down. As with the zoom control, click and hold the mouse on
  the sphere, then drag the mouse in the appropriate direction to adjust the
  location of the terrain model. Let go, and the terrain will be redrawn.
- The hand in the square lets you pan the entire terrain model left, right, up,
  or down. Click and drag with the mouse to adjust the position of the terrain
  model on screen.

If you get the terrain model completely rotated, upside-down, or in some unknown
orientation, you can use the reset button to reset the perspective viewpoint
back to the default.

When done, click one of the other buttons at the top to go to another display
mode, or press ESC to return to 2D view. The rest of the buttons along the
bottom of the screen act normally.