I made a bunch of drawings to dimensions with the grid. But after sending them out for quotes I discovered the drawings are larger than desired. Same problem if I send drawings to the printer. They are not coming out as actual size. Is there a way to correct this?
The about page calls itself 0.46. The OS is Debian Lenny.
When file is re-opened the saved properties come up as px. When mm or inch is selected the correct sizing gets displayed, so the actual real values aren't altered. The printer I'm using is an HP all-in-one office pro L7780. When drawing is selected from file manager and sent to printer the resulting print job is printed larger than it should be (very close to dims. described below). When the file is sent from Inkscape as a print-job the file is printed pretty close to actual size called for in the drawing (good).
When the file is sent to an unknown system probably using adobe photoshop or other commercial application the drawings get interpreted as being larger than actual >>3.456" X 1.0431" for a drawing that should be 70mm X 21mm. This makes it impossible to create a graphical overlay that is going to fit properly onto anything it was drawn for.
Conclusion? Well it looks like printer and the unknown application are doing the same thing. And Inkscape controlling the print job does it right. Culprit has to be with how the file gets saved and re-interpreted. Files seem to grow about 25% in each dimension.
Up to now Inkscape uses 90dpi [2] when converting units [1] from and to px. The differences you see might be based on other applications or printers assuming a different default resolution (72 or 96 dpi) for the output device.
[1] «The other absolute unit identifiers from CSS (i.e., pt, pc, cm, mm, in) are all defined as an appropriate multiple of one px unit (which, according to the previous item, is defined to be equal to one user unit), based on what the SVG user agent determines is the size of a px unit (possibly passed from the parent processor or environment at initialization time). …
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Note that use of px units or any other absolute unit identifiers can cause inconsistent visual results on different viewing environments since the size of "1px" may map to a different number of user units on different systems; thus, absolute units identifiers are only recommended for the width and the height on outermost 'svg' elements and situations where the content contains no transformations and it is desirable to specify values relative to the device pixel grid or to a particular real world unit size.»
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Scalable Vector Graphics (SVG) 1.1 Specification
W3C Recommendation 14 January 2003
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[2] The currently hard-coded value of 90 dpi is based on the CSS2 specification, detailing:
«Pixel units are relative to the resolution of the viewing device, i.e., most often a computer display. If the pixel density of the output device is very different from that of a typical computer display, the user agent should rescale pixel values. It is recommended that the reference pixel be the visual angle of one pixel on a device with a pixel density of 90dpi and a distance from the reader of an arm's length. For a nominal arm's length of 28 inches, the visual angle is therefore about 0.0227 degrees.»
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Cascading Style Sheets, level 2 CSS2 Specification,
W3C Recommendation 12-May-1998
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Note: in later revisions of the CSS2 specification the definition for the reference pixel was changed:
«Corrected the suggested reference pixel to be based on a 96 dpi device, not 90 dpi.»
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