Options
Opens the Warp Options dialog box in which you can define the warp parameters, load point pairs, and/or save point pairs. In order to perform a warp, you must locate two or more pairs of points.
Cancel/Finish
Allows you to cancel or execute the command. Once you have entered the minimum number of required pairs of points (as determined by the Model type), the Finish button is enabled. Clicking Finish warps the selected raster image based on your input. You can, however, click Cancel at any time.
Zoom
Allows you to modify the zoom factor for the zoom window. When the Zoom button is clicked off, the Zoom factor list is disabled; when the Zoom button is clicked on, the Zoom factor list is active. You can choose a zoom factor from 1 to 10. When Zoom is enabled and you click on an image, a new window opens to show you the area that you zoomed in on by the amount specified in the Zoom factor list. This allows you to refine the location of the point you placed in the main image. If Zoom is on, you must place perform a "refining" click in the Zoom window to get the point selected and to hide the Zoom window. The software will then prompt you for the next point. Clicking the next point again opens the Zoom window where you can refine the selected point. This sequence continues until you click Finish on the Multi-Point Warp ribbon.
Model
Specifies the model (Helmert, 1st Order Polynomial, or Projective) on which you want to base the image transformation or warp. Projective is not listed as a model type unless Resample is selected on the Warp Options Dialog Box. The model you select determines the minimum number of required source/destination points, as well as how the selected image is transformed.
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Helmert - This model, sometimes referred to as an Orthogonal warp, performs a general data file rotation, X and Y axes translations, single value scaling, and orthogonality of perimeters. This warp is proportional and cannot be "rubber sheeted". The minimum number of points is 2, and will also create residuals if more than 2 point pairs are selected. In effect, the Helmert warp operates more like an interactive scale and rotate function. No distortion is created with this method. General use includes engineering type applications.
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1st Order Polynomial - This model uses a first order polynomial to mathematically best fit the data. This is the stereotypical "rubber sheet" warping. A minimum of three point pairs will ensure that the source/destination points are placed exactly, while other portions of the drawing will be placed as close as mathematically possible.
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With 3 point pairs, there will be no residuals (errors).
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Projective - Projective warping will determine exact placement of 4 control points (corners). Although this warp is categorized as a Linear warp, second order polynomials are used to determine the location of the fourth point. This model eliminates the "best fit" results of Affine warping when applied to rectangular data. While accuracy of the fourth point is substantial, the time required to calculate results using this model is also substantial an may deter use with large data sets.
With all models, selection of more than the minimum number of points will introduce residuals (errors). For warps with no residuals, use the following number of point pairs: 1st Order Polynomial (3); Helmert (2); Projective (4).Keep in mind that no residuals does not necessarily produce the best or desired results.
To use this functionality, you must install the Image Integrator option.