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The AutoCAD Interface

Introduction to the AutoCAD Interface

ASRix and AutoCAD enjoy a symbiotic relationship wherein AutoCAD provides a 3D geometry and display environment and ASRix provides rectified images to build 2D and 3D photo mosaics. If an AutoCAD drawing has the points necessary for rectification those points can be selected and passed to ASRix and, because the rectifier knows everything about the geometry of the image it can pass that information back to AutoCAD so that the image can be inserted, scaled and correctly oriented in 3D space.

Exactly how this works and which features are used is configured through the settings utility.

The following brief explanation assumes that, in the settings, everything is turned on.

When you launch ASRix from within AutoCAD you can use a variety of AutoCAD functions to determine the image to be rectified. The options include:

AutoCAD stores the file name for future action then launches ASRix.

You select the image coordinates in ASRix in the usual way though, if your AutoCAD drawing contains entities drawn with the points you need for rectification you need not enter the real world coordinates (actually should not, as they will be overwritten anyway). You should also specify the OHV of the coordinate system at this time. When you save the file you will be returned to AutoCAD, OSNAP (end) will be enabled, as you need the precision and a 3D point cannot be selected without it. You will then be prompted, one point number at a time, to select the equivalent points in the drawing. The coordinates extracted from the drawing will be used to update the .PTS file for the image on which you are working.

Again ASRix will start this time, with the image rectified based on the points you just selected. IF your points are good you may only have to rearrange the OHVs or fine tune the placement of the image points and re-rectify to obtain satisfactory results. If there are wrongly placed image points or errors in your field notes (out of sequence point numbers, illegible notes, etc) there are some trouble shooting options to help you sort things out.

When the rectification is satisfactory and the file is saved you will be returned to AutoCAD for the insertion of the image.

First you will be asked to select any CAD entities that you want to appear over the image (you won't be able to see them afterwards). Typically you choose entities that will help you determine the quality of the rectification and insertion.

The image will then be inserted into the AutoCAD drawing using the coordinate system defined by your selection of OHVs and to the scale determined by the rectification.

AutoCAD will then adopt a plan view of the inserted image and prompt you to trim the image by selecting points on it. Unfortunately this is as far as we've been able to automate this. To see the entities you selected to appear in front of the image you will have to use AutoCADs REGEN command.

If the points you selected in AutoCAD are consistent with those you chose in ASRix everything is as it should be. If not there are tools that will detach the image and return you to the rectifier or even to insert the original, un-rectified, image as a place holder while you return to the field to figure out what is wrong.

As mentioned earlier the settings utility determines which of these options will be invoked and the ASRix menu for AutoCAD provides commands for these functions as well as a number of utilities to help you find your way around 3D space, determine point coordinates, trim, annotate and otherwise manipulate the images. There is a detailed description of each command in the section that follows.

Next The ASRix Menu in AutoCAD


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Inquiries to: steve@icomos.org

Generated by: CART
(Thu Sep 20 17:56:25 2007 )