Pitney Bowes MapXtreme - Manual (Page 424)

Chapter 23: Workspace Manager
Layer Control
MapXtreme v7.1 431 Developer Guide
• Always–Raster reprojection is always performed. MapXtreme calculates the image’s
coordinates based on a precise formula and then the pixels are resampled using either the Cubic
Convolution or Nearest Neighbor methods.
Use the Reprojection Resampling settings to specify a resampling method for the reprojected raster
image.
Resampling is a method of restoring the pixel value (usually proportional to the brightness of a spot
on the ground object covered by the instant field of view of the image sensor) of the destination
raster image based on the source image being a discrete representation of the initial continuous
brightness field.
The pixel values of the destination image can be calculated using one of two resampling methods:
Cubic Convolution and Nearest Neighbor. Choose one of the following:
• The Cubic Convolution method provides the best "restoration" of pixel values because of their
discreteness. In Cubic Convolution, a pixel in the destination image is calculated based on the
pixel values in a 4x4 pixel window centered at the basic pixel in the source image. The
coordinates of the basic pixel are calculated for every pixel of the destination image based on a
special optimized procedure. Pixels are then weighted based on the basic pixel coordinates. In
general, we recommend that you use the Cubic Convolution resampling method for aerial
images and satellite raster images to get a better image quality.
1
• The Nearest Neighbor method replaces the pixel value in the reprojected image with the base
pixel value from the source image. This resampling method takes less time to render than the
Cubic Convolution method, but it may be less precise. In general, we recommend that you use
the Nearest Neighbor resampling method for raster maps, grids, and scanned maps to get faster
results.
To change the rotation angle of the raster reprojection, go to the View tab, provide an angle and click
Apply. See
View .
Layer Settings
When you click on a map layer node in the Layer tree, the following tabs are available in Layer
Control.
Visibility
Select the Visible check box to make the map layer visible. Selecting the check box next to the layer
in the layer tree has the same effect.
Select the Display Within Range check box to specify either a zoom range or scale range in which
the layer appears. If you select a zoom range, specify the minimum and maximum zoom in miles.
The layer appears within this range. If you select a scale range, specify the closest and farthest
scale. The layer appears within this scale range.
1. The Cubic Convolution algorithm used in MapXtreme is based on the work of S.K. Park and R.A.
Schowengerdt, Computervision, Graphics and Image Processing (1983, Volume 23, pp. 258-272).