Bricscad Issues - U.S. Paper Sizes Are Incorrect

2012-06-07

2014-06-04 UPDATE: I’m still having some American paper size problems in the latest V14...

2012-06-14 UPDATE: Bricscad said they can verify this problem, and they are looking into it.

I am in the U.S., so I work with U.S. paper sizes. The paper sizes I most commonly work with are Letter, Tabloid, Architecture D, and Architecture E1. This analysis is going to focus on those paper sizes, but I'm sure the issue applies to all U.S. paper sizes.

Problem Description

In Bricscad, if you choose a U.S. paper size, you get something that is not exactly the correct dimension. It is off by a small amount. It turns out that Bricscad is thinking of the paper size in even millimeters, and then converting that to inches, which introduces an error.

Demonstrate The Problem

Here are the steps to demonstrate the problem:

1. Start a new drawing from scratch
2. Select 2-D context and Imperial units
3. Go to "Layout1".
4. Right-click on "Layout1" and choose "Page Setup..."
5. Click to edit "Layout1"
6. Select a printer that is capable of using Letter paper.
7. Select a paper size of "Letter"
8. Exit out of Drawing Explorer and make sure you are still on Layout1
9. Draw a rectangle, using coordinates, from "0,0" to "8.5,11"
10. You now have a pline rectangle overlaid on a representation of paper
11. Zoom in on the top right corner of this rectangle
12. Verify that the rectangle is exactly 8.5x11, but the representation of paper is not.

Here is an alternate way to verify the problem:

1. Create a page layout using a U.S. paper size, and imperial units, as described above.
2. Use a virtual PDF printer, like CUPS-PDF, to print that layout to a PDF.
3. Open the resulting PDF with your favorite viewer, and look for the "properties" of the PDF.
4. The viewer will show a page size that is not exact, something like 8.51 x 10.98

Please download this PDF, which was created with Bricscad, to see an example of PDF output that has the wrong paper size. It should be 11.00 x 17.00, but instead it is 10.98 x 16.97.

What's Happening

Here are the exact paper sizes for the papers I use most commonly:

Those paper sizes are exact and have been around for a long time.

Somehow Bricscad is using a metric approximation of the paper size, then converting that back to inches, which introduces an error. The following table tells the whole story. The first data column has the exact size of the paper in inches. The second column has the exact size of the paper in millimeters. The third column has the size of the paper rounded to the nearest millimeter. The fourth column has that rounded size converted back into inches. Finally, the last column has the amount of error that this rounding introduces, in inches.

Somehow, surely this must be an oversight, Bricscad is using the farthest-from-the-truth fourth column as the size of U.S. papers. It's the size of the paper, rounded to the nearest millimeter, then converted back to inches.

I hope the table explains the problem adequately. CAD drawing is an exacting medium, and I hope this problem can be fixed easily.

Another Possible Culprit

It is possible that paper sizes are defined by my operating system, and Bricscad is polling those paper sizes to know what it should display. That's possible. But I have never noticed any problem with my paper sizes before this time.

Do Windows users, who use U.S. paper sizes, notice this error also?