Ever wondered the best way to convert PDF to CAD? Well, today we’ll take you through everything from what a PDF is to common problems you may find when converting PDF to CAD.
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What is a PDF file?
PDF stands for Portable Document Format. A PDF file can originate from a variety of sources such as word processing, page layout programs, document scanners, print drivers and many other programs.
An advantage of PDF files is that Adobe Acrobat PDF reader comes installed on most computers, so users can view PDF files with no problems. PDF files can also be viewed in most web browsers.
What is in a PDF file?
- A PDF file may contain one or more pages.
- Each page may contain any combination of 2D vector graphics, text or raster images.
- The PDF vector graphic objects(entities) are limited to fairly simple types such as lines, beziers, polygons etc.
- PDF files allow for very fine positional accuracy of text. Words and sentences are often held as a set of individual characters, each with associated positional and style information.
- Single or multiple raster images can be placed in any position on a page. The encoding of each raster image can be one of many PDF supported types.
Issues with PDF to CAD conversions
PDF Vector Graphics
As indicated above PDF vector graphics are limited. In a vector PDF file, there are no CAD Arc or Circle entities. Arcs and Circles are either made up out of many short lines that are difficult to edit or out of Bezier curves.
Scan2CAD includes Make Vector Arcs and Make Vector Circle options. If you select these, Scan2CAD will replace the short lines or Bezier curves with true Arcs and Circles that are easy to edit.
To ensure Scan2CAD converts PDF entities to Arc and Circles select the following Scan2CAD Menu option before loading your PDF file into Scan2CAD:
File > PDF > Import Options.. > Make Vector Arcs
File > PDF > Import Options.. > Make Vector Circles
If you wish to convert PDF vector lines that represent curves to Beziers then select the following Scan2CAD Menu option before loading your PDF file into Scan2CAD:
File > PDF > Import Options.. > Make Vector Beziers
PDF Line Types
A PDF file may contain user defined line types (e.g. a line comprising a sequence of dashes and dots of varying lengths and order). Where these line types have been used, Scan2CAD identifies them and saves them accurately to the DXF file.
There are no user required settings as Scan2CAD will automatically retain User-defined line types when loading the PDF file.
PDF Line Widths
A PDF file may contain line width information associated with each PDF vector entity. Scan2CAD retains the line widths used in the PDF file while giving you the option to turn them off when saving DXF.
There are no user required settings as Scan2CAD will automatically retain line width data when loading the PDF file.
To display the vector line widths within Scan2CAD then select the following Scan2CAD Menu option:
View > View Vector LIne Widths or toggle the lines width view by using the Shift+L keyboard combination.
If you do not wish to use the line widths data when exporting the vector image to a DXF file then un-select the following Menu option:
File > Vector > DXF Export Options… > Include Line Widths
As previously stated PDF files allow for very fine positional accuracy of text. Words and sentences are often held as a set of individual characters, each with associated positional information. The “reassembly” of these characters into strings is challenging. If it is not optimally done, the text in the resultant DXF file may be made up of discrete characters and split words that are very difficult to edit.
Scan2CAD uses high quality “reassembly” of characters into words and sentences, making the text easy to edit in your CAD program.
There are no user required settings as Scan2CAD will automatically convert PDF characters into words and sentences when loading the PDF file.
However, a PDF file may contain text that has been produced specifically for the purposes of doing a search of the PDF file. This text may be of varying quality, size and accuracy dependent on the OCR package used to produce it. Such text may not be required to be loaded into Scan2CAD.
If you do not wish to load such text then un-select the following Scan2CAD Menu option before loading your PDF file into Scan2CAD:
File > PDF > Import Options… > Load PDF Text
PDF To CAD – Raster Images
A single PDF page can be made up of multiple raster images. Traditional PDF to DXF converters save each raster image as a separate raster file. Scan2CAD maps all the raster images into a single raster image file that can be edited or vectorized within Scan2CAD.
Another major benefit of Scan2CADs approach is that when saving a DXF file from Scan2CAD where you require the raster image to be included then you will only have a single raster file associated with the DXF file.
One PDF file we have tested includes several hundred arrow heads, each one a separate raster image.
PDF to CAD with Scan2CAD will convert this PDF file to one raster image:
If you convert the same PDF file in a traditional PDF to CAD converter you end up with hundreds of raster images:
The single raster image produced by Scan2CAD can be controlled by setting the following twoScan2CAD Menu options before loading your PDF file into Scan2CAD:
File > PDF > Import Options… > Color Raster as > BMP or JPEG
If BMP is selected then full color raster image accuracy will be retained when the file is exported.
If JPEG is selected then there will be a reduction in color raster image accuracy when the file is exported but the exported file will be smaller.
Please note that black and white images are always exported as TIF (Group4).
File > PDF > Import Options… > Limit Raster max DPI
If the single raster image produced by Scan2CAD has a very high DPI then you may find that due to the memory constraints of your PC that it is not possible to load the image.
If this happens then try setting max DPI to a smaller value before attempting to reload the PDF file.
Scan2CAD is Avia Systems’ market leading software, helping users around the world to convert with intelligence and edit with precision every day. Visit our ultimate guide for the full information on how to convert from PDF to DWG—or discover more about PDF to DXF conversion here