Perspective/Fly Through Modification

This form controls the perspective views that make up overflight movies, live flying, or the single perspective view.

You can modify the perspective view by double clicking on the image, or selecting the Modify menu choice.

General Viewport Viewer Stereo Drape Flight options Image quality Gazetteer

 Method is selected from the drop down list on the bottom left:

  • Fishnet: terrain surface is represented by a grid of colored lines generated from the DEM. You can select either ChromaDepth  or regular fishnet. Because of the black background, this option is not recommended if you want to print the image. Both fishnets probably now appear primitive with today's typical processing power, and should probably be avoided.
  • Reflectance: elevation data is displayed as a gray scale, shaded relief with synthetic illumination. This provides a more natural display of elevation features, similar to grayscale panchromatic satellite imagery, but is generated solely from the DEM.
  • Draped: the current map window draped over the DEM, which can include map overlays. You must select the draped view initially, and cannot switch to a draped view later.
  • None (ridges only)

You can switch the method once the view is drawn, but the draped option is only available when first selecting the view.

Reset Defaults: return to the program default conditions for the perspective and fly through.

Save to file saves the view parameters to disk. (Under development, and will break any time the view parameters are significantly changed or enhanced.)

Read from file restores view parameters from disk.


General Tab

  • Distance Between Profiles (m): distance between profiles in meters. Consider the data spacing (small profile spacing with large data spacing does not make sense) and remember that the smaller this number, the longer drawing the profile will take. This only affects wire frame views
  • Mesh Spacing (m): separation in meters of the mesh that runs front to back in the image. These lines converge toward the back of the image. This only effects wire frame views.
  • Distance to first profile (m): how much terrain immediately in front of the observer to ignore. This precludes a small hill immediately in front of the observer from blocking everything.
  • Points spacing on radial: This determines the resolution of the view and the time it takes to draw (better means longer). The default puts the point spacing along the radial equal to the DEM spacing (or the image resolution in the case of draped imagery), which should probably give optimal image quality. If this number is excessive you may wish to decrease the number.
  • Clouds: you can place an image with clouds in the sky
  • Custom perspective sky: you can set the sky color.
  • Min sky to show: when you first draw a view, this determines how much sky will appear at the top of the view.  It has no effect when you redraw an existing view.
  • Ridge crests
  • Checkboxes control:
    • Remember vertical viewport:
    • Label Viewport: label vertical and horizontal angles, and the location of the viewer on the bottom of the window.
    • Title Viewport:
    • Flying danger colors:
    • Viewshed fan on map:
  • Reflectance (illumination) parameters: only affect the reflectance view, but can dramatically affect the view.
Viewport Tab
  • Maximum vertical Angle: The default should be accurate, but you can vary to match an adjacent profile or if unusual terrain causes part of the region to be off screen. This in effect controls vertical exaggeration. The vertical angles are labeled on the left side of the view. Computed from Pitch and VFOV.
  • Minimum vertical Angle: The default should be accurate, but you can vary to match an adjacent profile or if unusual terrain causes part of the region to be off screen. This in effect controls vertical exaggeration. The vertical angles are labeled on the left side of the view. This will probably be a negative angle.Computed from Pitch and VFOV.
  • Pitch:
  • Vertical field of view:
  • Viewport depth (m): nothing beyond this depth will be drawn, so it controls whether mountains on the horizon will be drawn.  The tradeoff for showing the horizon (which might be blocked, or obscured by smoke or haze) is increased drawing time.
  • Observer elevation; one choice will be active depending on whether you are set for Nap of the earth or not.  The higher above the ground the less will be blocked.
    • Observer above ground (m):
    • Observer elevation (m ASL):
  • Vertical exaggeration is set from the FOV and image size selected, and not picked directly.
  • Observer Elevation for Flight can be either:
    • Nap of the earth--constant elevation above the ground.
    • Constant elevation--specified elevation above sea level.
  • Set Sensor Pitch: which can be shown on the view.
Viewer Tab
  • Move the viewer a specified distance in a given direction.
  • Enter new location from the keyboard.

Stereo Tab

Anaglyph 3D views for red/blue glasses, with a choice of two options:

  • Shift view: affects the Anaglyph, displace options
  • Dual view: affects the Anaglyph, two scenes option

Drape tab:

  • Show grid on drapes: for a draped map, you can either hide or show the grid.
  • Show overlays on drapes: for a draped map, you can either hide or show all overlays (weapons fans, range circles, vector files) .
  • Drape map without redrawing: for faster operation, with lower resolution, you can use a single map to drape all frames, which will show any one time drawing on the map.  Otherwise the program will redraw the drape map, at maximum resolution for the required area, for each frame unless your view is still entirely on the last drape.
  • Max size drapes, x and y dimensions

Flight options Tab

  • Frame separation--distance between movie frames in meters.
  • Move name
  • Show flight map--the location of each view can be displayed on a location map for each frame of the movie.
  • Side by side windows--if the flight map is not side by side, it will be below the view. Which is better depends on the size of the movie frames, the aspect ratio of the movie and the map, and the size of your screen.
  • Default new movie names:
  • Live flying movie: saves live flying as a movie.
  • Dual fields of view: you can get two views for each frame, one zoomed in and the other wide angle.  This will double the size of the movie, and the movie can only be played inside MICRODEM.
  • Dual drape maps: for added realism, at the cost of addition time, each of the dual fields of view can have its own drape map with tailored resolution.
  • FOV1:
  • FOV2
  • Cross track profiles:
    • Show or hide.
    • Height and distance to look on either side.
  • Along track profiles:
    • Show or hide.
    • Number of profiles to show on either side.
    • Distance between profiles.
    • In this case you would get the elevations at 250, 500, 750, 1000, and 1250 m on either side of the flight path.

Image quality Tab: perspectives are drawn using points along the radials. To speed up the operation, you can vary the spacing along the radial. Because you have more detail visible close in, the program can use smaller distances close in and then larger spacing farther out.

Range is the distance out to increase the spacing, and factor is the amount by which to multiply the base distance increment.

If the drape resolution is 1 m, out to a range of 5000 m the program will go every 1 m, determine if that pixel should be visible and where, and draw it. Beyong 5000 m, the program will go every 2 m (the 1 m spacing time the factor of 2), and beyond 10000 m the program will go every 4, and so on.

Gazetteer Tab:  Label features on perspective

Perspective Window Icons


Options, Units tab lets you select "feet" as the unit for some of the options on this form in order to be "aviator friendly."

If you hit cancel, nothing will change. If you hit OK, the image will be redrawn with the new parameters. Invalid input will leave the parameter unchanged.

Last revision 7/8/2015