Overview

This document describes the procedure for defining & placing raster data in a full-size working environment within MicroStation I/RAS B.

Working with Full-Size Units

If you want to use full-size units when you edit the scanned image of a drawing, you can create a full-size working environment with MicroStation I/RAS B. This enables you to edit the raster image of the drawing using the exact scale and units of the original.

If your drawing depicts dimensions that exceed the physical drawing size (if the scale uses miles, for example) you cannot scale the raster image of the drawing to a large enough size in MicroStation I/RAS B to use true measurements when you edit the raster file. Therefore, any dimensions or distance measured in raster units would not match the scale of the original hardcopy drawing.

If you want to work in a full-size environment, it can be very time-consuming to convert every measurement or raster item dimension from raster units to drawing dimensions with a conversion factor. The solution is to set the working units of the design file to match the linear units in your drawing. The working units can be anything from feet to miles, depending on your needs. Then, load the scanned drawing with precision key-in commands so that the drawing units match the working units. This enables you to work on the raster file using the same dimensional units to create the drawing.

For this procedure you must:

• Select full-size dimension units to accommodate the specific linear scale of the original drawing (miles, feet, or meters, for example).
• Display the size of the scanned image by previwing the drawing.
• List the scale of the hardcopy drawing.
• Use the full-size dimension units to set the working units in the design file. The size of the scanned image and the scaling of the hardcopy drawing provide you with the values you need to calculate the key-in points and place the raster file correctly.

To work with full-size units in MicroStation I/RAS B

1. Set the working units of the design file to match your drawing units.
2. Preview the raster file. Note the raster file width & height.
3. Calculate the scale of the drawing. This can be a number like 1 drawing inch = 5 miles for a map, or 1 drawing inch = 10 feet for a building plan. A drawing inch is equal to a raster inch.
4. Calculate the size of the raster file dimensions in raster inches times scale units per raster inch. This will provide you with the raster file corner points to key in when you open the file.
5. Open the file, and position it with a MicroStation precision placement key-in. Use the points that you calculated in the previous step.
6. Measure the distance between two points of known distance to verify the procedure.

Note: Your raster file should be set to display all measurements and item sizes in full-size units.

Example Scenerio

Assume you have a drawing with the following characteristics:

• Full-size dimensions : feet
• Raster file size: 20 inches long, 30 inches wide
• Drawing scale: 1 inch = 10 feet (1:10)

To load this raster file into a full-size environment:

1. For a file scanned at 1000 dpi, set the working units to MU: ft, SU: 12 inches, and PU: 10,000. Always allow 10 PU (UORS) per pixel to avoid round-off errors.
2. The corner point key-in calculation is: 20 raster inches times 10 feet per raster inch = 200 feet and 30 raster inches times 10 feet per raster inch = 300 feet. If you want to place the upper left corner of the raster file at the design plane origin, the key-ins are:

   xy=0,0 (upper-left corner)
   xy=300,-200 (lower-right corner)

These key-in commands place the raster file such that all measurements taken and all raster items added assume the dimensional units of the original drawing. This technique enables you to place a raster file at a specific location within the design plane that mirrors the scale of the original drawing.

See Also

Product TechNotes and FAQs

Raster Product TechNotes And FAQs

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

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