Easily Clean Up Noisy Raster Reference Files

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Without leaving MicroStation

By Eiren Smith, Professional Raster Reference File Wrangler

Do you work with scanned drawings, such as TIF or CIT graphics files, referenced to MicroStation DGN files? Do you notice that they never seem to be perfectly level and they’re often full of noise? Do you currently have to fix them outside of MicroStation, or in a complicated MicroStation add-on product like I/RAS B or Descartes? Wouldn’t it be great if there was a way to make this cleanup simple and easy?

RasterDgn Despeckle Before and After

Figure 1. Whether you need to copy, move, delete an area, automatically deskew, crop or despeckle raster reference files, RasterDgn does the job quickly and easily and lets you get back to working on your project.

In a previous article [RasterDgn Makes it Easy to Permanently Deskew Raster Reference Files], we discussed how to automatically deskew your raster reference files. In this article, we’ll cover how easy it is to despeckle (clean up noise in) your raster reference files using RasterDgn.

Despeckling Made Easy
One of the first things MicroStation users usually want to do to clean up scanned legacy drawings they’ve attached to DGN files is to get rid of the noise in them. This noise could be due to small defects in their physical drawings or it could be a result of particles of dust or even dirt on the drawings or on the scanner that was used to create them.

Because most users scan their legacy drawings in monochrome (one color), it’s not possible to isolate these speckles based on their color. RasterDgn isolates these speckles by their size and it lets you choose the maximum anything-this-size-or-smaller-is-a-speckle threshold for any given despeckle job, giving you the ability to increase the intensity of the despeckling operation when needed. Most of the time, users leave this set at its mildest setting, 1×1, meaning that only points the size of one pixel will be treated as speckles. Anything bigger would be considered real data, not noise, by RasterDgn.

Here’s How to Use It

  1. First, open the DGN with the raster reference attachment you want to remove speckles from.
  2. Load RasterDgn by choosing Axiom | RasterDgn. The RasterDgn toolbar will display.
  3. Push the {Despeckle} button. Its icon is a little vacuum cleaner cleaning speckles out of a tiny little raster file.
  4. A box will appear in which you can choose what area to despeckle and how aggressively to despeckle it. The choices are “All”, “Block” and “Fence”. Today, I’ll leave it set to “All” (the default).

    RasterDgn's intuitive interface makes despeckling easy.

    Figure 2. RasterDgn’s intuitive interface makes despeckling easy.

  5. If you have more than one raster reference attachment in your model, you will need to click on it once to identify it and start the despeckling operation. If you only have one raster reference attachment in your model, you can click anywhere in a MicroStation view to start the despeckling — you don’t have to click on the raster itself.
  6. A box will pop up telling you how many speckles RasterDgn found in your raster file. Press {OK} to let it remove those speckles. It is common to encounter tens of thousands of speckles, but everyone’s files will vary.

    With just a few clicks, you can quickly clean up raster reference files and you don’t have to send your users away for training to learn how to use it. It’s really that easy.

    Figure 3. With just a few clicks, you can quickly clean up raster reference files and you don’t have to send your users away for training to learn how to use it. It’s really that easy.

The speckles in your raster file disappear immediately. That’s all there is to it! RasterDgn has a well-defined focus. It’s easy to use, saves you time and lets you do the things you really need to do, without unnecessary complications. Its job is to help you get real work done with minimal fuss. Anyone can use it because of its clean design and focus.

Get a Free 45-day Lease and See for Yourself
Call 727-442-7774 extension 3807 now and we’ll send you a free, fully functioning 45-day lease of RasterDgn so that you can see for yourself how easy it is to use. You can also get more information about RasterDgn by visiting Axiom.

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