Merging

V. Merging. At this point, you should have copies of all your sketch-maps that have been scaled, trimmed and morphed. In the next step, we are going to combine them all into a single image.

A. Load First Image. At the main window, press the Load button and load the first sketch-map image.

If it is a long narrow passage, the first image in your merge will probably be the sketch-map for the first shots in the survey. If the passages are more complex, you may want to the think about the best sequence to combine the sketches. Now press the Merge Button. The will bring up the Merge Tool.

B. Load Merge Image. We will now load the image that will be overlaid on top of the main image. Press the load button in the lower left corner and select the second sketch in the survey

At this point, the first image will appear in the right hand window and the second image will appear in the lower-left window. The second image will also appear overlaid in the right hand window.

C. Moving, Sizing and Rotation. The overlaid image will appear enclosed in a red frame. The frame can be used to move, resize and rotate the overlay image. Dragging the green dot at the top rotates the image. Dragging the square boxes at the corners, resizes the image. Dragging the interior of the box moves the image. Since we have already scaled and rotate all our images, we only need to position the image.

D. Image Transparency. The image is also partially transparent. The black parts of the image remain opaque while the white parts are transparent. Since the background of most sketch-maps is white, this allows the underlying image to be seen through top image. This makes it easy position the image for merging. It also allows the lines from both images to blend together when the images are merged.

If the background of your images is not pure white, the background may not be as transparent as you would like. You can make an off-white background more transparent by adjusting the "White Level" sensitivity.

5. Auto Expansion. As you drag the overlay image around the screen, the underlying image will automatically expand when the edge of the overlay reaches the edge of main image. In this way the image is automatically expanded so the overlay always fits. This works for the top, bottom, left and right sides of the image.

Note: If you are working with large images, you should be a little careful about how much you let the images expand. Since the number of bytes in the image goes up with by square of its dimensions, you can run out of memory if you aren't careful.

If you have made the image larger than necessary, you can undo the size change using the Undo Button. You can also trim the image with Editor when you have finished merging.

F. Final Positioning. The final step is to position the overlay sketch-map so the two images fit together perfectly. Since we have already scaled and de-rotated our images, all we have to do is move the overlay to the correct position. Simply move the overlay until the common passage walls and survey stations match. Since the overlay image is transparent, this will be easy to see. In fact, if the sketches were accurately drawn you should have little trouble getting everything to line up.

When you are happy with the alignment, press the "Merge" button on the tool bar. The two images will be combined into a single image.

G. Merging More Images. You can now add additional sketch-maps to the combined image. Just follow steps B through F for each of the rest of the sketch-maps. You may want to exit periodically (by clicking OK) to save your work.

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