Adjustment points in quick drawing of the grid
In the Coordinates of first cross field, specify the coordinates of the first cross on the raster. For typical map sheets, this is the left-bottom corner of the map. If the source raster is inserted "more or less" in the target location, you can leave the default option Cross nearest to the fisrst clicked cross on raster checked. The programme will then automatically calculate the coordinates of the nearest cross, based on the scale set in the Spacing field. If we are calibrating a scan of a standard map sheet with a known ID, we can use the Map ID .... button. After entering the map ID, all necessary parameters will be set (provided if the ID is recognised by the programme).
A slightly different procedure can be adopted for non-standard maps, especially those that contain a twisted grid of crosses, and other maps where the left-bottom corner cannot be determined. We can always start the calibration from any cross with known coordinates. The option Automatic determination of the number of crosses should be checked. In this mode, you do not need to specify the number of rows and columns in advance, as the programme will automatically calculate all places where crosses can be located. It is only important that as soon as the first cross is indicated, the next cross clicked is the one to the right of the first cross clicked.
When you have finished setting up the options, click the Start button and proceed to point to the crosses in the drawing window, starting with the first cross (left-bottom).
By default, the crosses are pointed in order from left to right, bottom to top. When the option Automatic determination of the number of crosses is enabled, the order is variable as the programme tries to 'go through' all the crosses on the raster.
To skip pointing to any crosses (e.g. when a cross on the raster is unreadable or outside the raster area), click anywhere with the right mouse button (reset).
To stop pointing of crosses one should: - click any tool button (MicroStation), - click the Cancel button, which should appear in the corner of the desktop during calibration.
Once all the crosses have been indicated, there are calibration vectors in the form of lines connecting the points on the raster to the target locations on the drawing.
Continue in the same way as when specifying the adjustment points using lines as standard: - click , - select the Read control points from last editing layer.
The adjustment point data will from then on be visible in the table on the Warp tab.