Using the Warp processes
There are three types of Warp processes: Warp-Affine, Warp-Grid, and Warp-SRS. These processes can be applied only at the raster level.
Warp-Affine process
The Warp-Affine process enables you to perform an affine transformation, or affinity. This process is automatically included in the process chain when you add a georeferenced raster to your image service definition.
The affine type represents a linear transformation that preserves collinearity, parallelism, and ratios of distances. While an affine transformation preserves proportions of lines, it does not necessarily preserve angles or lengths.
In general, an affine transformation is a composition of rotations, translations, dilations, and shears. It has 6 degrees of freedom (parameters) A0, A1, A2, B0, B1, and B2, used in a well-known formula:
X = A0 + A1 * x + A2 * y
Y = B0 + B1 * x + B2 * y
where
A0 = X-offset
A1 = X-col
A2 = X-row
B0 = Y-offset
B1 = Y-col
B2 = Y-row
These parameters are detailed in the table below.
|
Parameter |
Constant |
Description |
|---|---|---|
|
Direction of initialization |
Direction in which the transformation will take place. |
|
|
X-offset |
A0 |
X-offset for the image-to-ground transformation. |
|
X-col |
A1 |
Column coefficient for the x-coordinate in the image-to-ground transformation. |
|
X-row |
A2 |
Row coefficient for the x-coordinate in the image-to-ground transformation. |
|
Y-offset |
B0 |
Y-offset for the image-to-ground transformation. |
|
Y-col |
B1 |
Column coefficient for the y-coordinate in the image-to-ground transformation. |
|
Y-row |
B2 |
Row coefficient for the y-coordinate in the image-to-ground transformation. |
|
Alias |
An alias for this process. An alias should uniquely identify the process in a process chain. You can edit this alias without affecting the process. |
Warp-Grid process
The Warp-Grid process enables you to perform a two-dimensional warp based on a grid of points.
The parameters represent a regular grid of points in the output coordinate system, each point being associated with an x,y coordinate in the input coordinate system. The grid of points forms cells. For each output coordinate, an associated input coordinate is computed using bilinear interpolation within the associated cell. If a coordinate outside the grid is selected, a bilinear extrapolation of the nearest cell is performed.
The grid is described by either upper left corner (default) or lower left corner, number of rows and columns, and the (x,y) coordinates of each point within the grid.
|
Parameter |
Description |
|---|---|
|
Upper left X |
The upper left x-coordinate of the grid. |
|
Upper left Y |
The upper left y-coordinate of the grid. |
|
Number of columns |
Number of columns in the grid. |
|
Number of rows |
Number of rows in the grid. |
|
Size of each column |
Size of each column in the grid. |
|
Size of each row |
Size of each row in the grid. |
|
X values |
Values of the x-coordinates, entered row wise. These values should be separated by a comma. |
|
Y values |
Values of the y-coordinates, entered row wise. These values should be separated by a comma. |
|
Alias |
An alias for this process. An alias should uniquely identify the process in a process chain. |
Warp-SRS process
The Warp-SRS process allows you to transform coordinate systems. It enables ArcGIS Image Server to convert the request from the service coordinate system to the raster coordinate system.
|
Parameter |
Description |
|---|---|
|
Direction of initialization |
Direction in which the transformation will take place. |
|
Input SRS |
The spatial reference system of the input points. |
|
Output SRS |
The spatial reference system to which the input points will be transformed. |
|
Alias |
An alias for this process. An alias should uniquely identify the process in a process chain. |