VTBuilder
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Strumento Area

Menus:

• Area Tool
  • Set to Full Extents
    • Resizes the area tool to surround all of the currently loaded layers.
  • Set to Layer Extents
    • Resizes the area tool to surround the currently selected layer.
  • Numeric Values
    • Allows you to examine and manually enter the range of the area tool.
  • Match Area and Tiling to Layer
    • This is useful when you will be tiling your terrain, and you want to sample your data at its exact, full resolution.  See Match Area and Tiling to Layer Dialog below.
  • Merge & Resample Elevation
    • Displays the Merge and Resample Elevation dialog (see below)
  • Merge & Resample Imagery
    • Displays the Merge and Resample Imagery dialog (see below)
  • Generate Vegetation
    • See Vegetation for an description of how to use this command.
  • Request Layer from WFS
  • Request Layer from WMS
    • These are experimental commands.  If you know how to use a WFS or WMS, give them a try!

Toolbar:

• The Area Tool () can be used to set the desired area directly with the mouse.  Click on any edge of the area tool to move that edge, or click inside to move the whole area without resizing.

Merge and Resample Elevation Dialog

You can choose where the output will go: To a new layer (in memory), To a file, or To a tileset (folder of tiles).

This dialog displays:

• The size of the Save Area, in either meters or degrees
• An estimated Sample factor, which is a guess based on looking at the X spacing of the first elevation layer.
• The projected Size at that density, which shows you the size of a grid that would result from sampling the area at the indicated sample factor.  Assuming that your input layers are of the same density (spacing), this indicates the approximate grid size of the indicated area.

Output to a new layer or to a file:

You can change the sample factor to see the projected size change.  Once you have a good idea of what output size you want, specify it in the "X size" and "Y size" fields.

Note that there is a helpful "Powers of 2 + 1" constraint you can use to limit the output to sizes which are supported by Terrain LOD, which is highly desirable at visualization runtime.

For effective visualization it is recommended that you pick a output size that is at least as large as your input data, but within the limits of your computer's RAM.

Output to a folder of tiles (Tileset):

This option has no limit on the size of the data.  Press Tile Options for the Tiling Options dialog.  Give the output a filename, and set the number of rows and columns of the tile grid along with the tile size (LOD0 Size) which gives the highest resolution of each tile.  The Information display helps you see whether your tiling is a good approximation of the input data your are resampling.  For smoother visualization, is it good to keep the tile grid size large and the LOD0 Size small (512 or less) so that there are shorter pauses as each tile is paged.  Alternately, if smoothness isn't a concern, you can decrease the tile grid size, and increase the LOD0 Size, which will result in a drastically smaller number of files on your disk.

See Enviro: Tilesets for a description of how tilesets are handled at runtime.  If you are using a tileset for your elevation, you must have a tileset of the same grid size for the imagery.

Merge and Resample Imagery Dialog

You can choose where the output will go: To a new layer (in memory), To a file, or To a tileset (folder of tiles).

This dialog displays:

• The size of the Save Area, in either meters or degrees
• An estimated Sample factor, which is a guess based on looking at the X spacing of the first imagery layer.
• The projected Size at that density, which shows you the size of a grid that would result from sampling the area at the indicated sample factor.  Assuming that your input layers are of the same density (spacing), this indicates the approximate grid size of the indicated area.

Output to a new layer or to a file:

You can change the sample factor to see the projected size change.  Once you have a good idea of what output size you want, specify it in the "X size" and "Y size" fields.

Note that there is a helpful "Powers of 2" constraint you can use to limit the output to sizes which are supported by the visualization runtime.

For effective visualization it is recommended that you pick a output size that is at least as large as your input data, but within the limits of your computer's RAM.

Output to a folder of tiles (Tileset):

This option has no limit on the size of the data.  Press Tile Options for the Tiling Options dialog.  Give the output a filename, and set the number of rows and columns of the tile grid along with the tile size (LOD0 Size) which gives the highest resolution of each tile.  The Information display helps you see whether your tiling is a good approximation of the input data your are resampling.  For smoother visualization, is it good to keep the tile grid size large and the LOD0 Size small (512 or less) so that there are shorter pauses as each tile is paged.  Alternately, if smoothness isn't a concern, you can decrease the tile grid size, and increase the LOD0 Size, which will result in a drastically smaller number of files on your disk.

See Enviro: Tilesets for a description of how tilesets are handled at runtime.  If you are using a tileset for your imagery, you must have a tileset of the same grid size for the elevation.

Match Area and Tiling to Layer Dialog

This is useful when you will be tiling your terrain, and you want to sample your data at its exact, full resolution.  For example, if you have some elevation data with 10m spacing or aerial photos with 1m spacing, you will probably want your tile resolution to match this exactly, so that you are seeing your full original data without any sampling artifacts.

Set the area you are interested in, with the Area Tool, then give this command.  You should see the dialog Match Area and Tiling to Layer.

• Previous: This is your original area of interest, which we will try to match.
• Current: This is the current tiled area, as close as possible to the original area.
• Match Layer: This is the layer you want to match.  For example, if you have one layers at 2m and some others at 4m, you might want to tell the dialog to match the 2m layer.
• Layer Resolution: This shows you the resolution (X and Y spacing) of the selected layer.
• Allow Area to Grow/Shrink:  In case your desired area can't be matched exactly with tiling, the area will need to grow or shrink.  You can indicate which is allowable.  For example, if you are sampling elevation, you will probably not want to grow the area outside the bounds of your original area, because then you would be sampling from an area with no elevation, which is undesirable.
• Tile LOD0 Size: This is value you set.  Tiles have a number of levels of detail (LOD), which are numbered starting from 0.  Hence, the LOD0 size is the highest resolution of each tile, which is value we want to match to the input data.  For efficient paging at runtime, you should try to keep this value small (512 for elevation, 1024 for imagery).  You can make it smaller, for even smoother paging at the expense of more tile files.
• Tiling: This is the tiling that results from matching your desired resolution and area.

The tiling (area and number of tiles) is also shown visually in the main view.