This is a follow up to the DWF Precision article by Brian Mathews of the DWF Team Link to Article
By default, DWFs are plotted from AutoCAD at 400 DPI—but this is far below the limit for DWF (up to 60 million DPI!). In fact, as Brian’s article points out, with the resolution that DWF supports, “DWF can measure the continental USA with a precision of +/- 2.4 millimeters when using the maximum DPI and paper size settings.”
To change the resolution (DPI) at which DWFs are published in AutoCAD based products:
- Select the “DWF 6 ePlot” driver in the AutoCAD Plot dialog
- Select Properties
- Select the Custom Properties icon (in the Device and Document Settings tab)
- Select the Custom Properties button
- Change the vector resolution—e.g., to 1200 or 2400 DPI
- Select OK
- Select OK
- Optionally save the changes to a different pc3 configuration file—e.g. with a 2400dpi suffix
- Select an output filename
- Select OK to plot to DWF
You could also just select ‘Custom’ in the dropdown list to set the resolution higher than 2400 DPI
For comparison I plotted a DWF and a PDF both at 2400 DPI:
DWF File Size on disk = 1.00 MB
PDF File Size on Disk = 5.23 MB
After opening the DWF in DWF Composer ($99) and taking a measurement with snaps and grabbing the geometry, I can see the section of interest is reported as 958' 8.94". Of course I could also just view the DWF in the free viewer. With DWF Composer I get redline markup, measurements, snaps, round trip the markup back to AutoCAD 2005 based products, and also a DWG viewer.
Checking the same section of interest in Adobe Acrobat Pro 6 (~$600), I had no real intuitive snaps and the distance was 8.11". I guess this is a miniature city ;-). "PDF: the right choice for itsy-bitsy cities and large hard drives".
With a higher DWF DPI setting, the advantages in terms of precision in the DWF files should become very clear when comparing DWF vs. PDF.
While 2400 DPI is sufficient for most needs, those using maps and GIS may need a higher DPI. AutoCAD allows for a Custom setting increasiong the DPI up to 60 million DPI.
Cheers,
-Shaan
