Raster to Vector Conversion for Building Renovation

Old Paper Construction Drawings

I live in an older city, with many older buildings…all of them designed and built well before the “digital age. “  As the city undertakes a revitalization project, renoolder buildingsvations to some of the older buildings will begin.   Architects, Engineers, and Contractors who are hired to facilitate these renovations will likely be handed an old set of mylars, vellums or worse, blueprints to work from.   How will they get these old drawings into a digital format for use in a modern day CAD program?

The most common way is to redraw them in whatever CAD program they’re using.  This is also the most inefficient way.   This method is not only time consuming, but it also lends itself to errors. Another option is scanning the drawings on wide format scanner and saving them as a .tif file. (.tif is the default file format for most wide format scanners)  A reliable scanning service bureau can scan drawings for a reasonable price, and will save eliminate the time-consuming process of redrawing.  Most CAD programs will import .tif files as an image but because it is a raster image and not a vector image, changes cannot be made to it in the CAD program.   The best that can be done is to draw on top of the CAD image, which may suffice for a minor renovation, but for major renovations, it will be necessary to go one step further and have the scanned raster drawing converted to a vector file.

Raster vs. Vector

What is the difference between a raster file and a vector file?  A raster file is a picture that cannot be manipulated, other than to do some very minor editing like you would do with a photo from your digital camera.  A vector file is more ‘intelligent’ if you will, and is the type of file used in CAD programs.   All parts of a vector file (CAD file) can be manipulated because every line, curve, font, symbol or other parts of the drawing exists as is its own individual object. This means that you can move it, make it bigger or smaller, longer or shorter;  you can turn it upside down, flip it over or color it differently.   This is why editing a CAD drawing for a renovation project is so easy…it can be done on the computer a viewed as it will look, even turned into an accurate 3D virtual model that can be digitally “walked through.”

Raster vs. VectorConverting drawings to vector files is something best left to a professional CAD conversion service.  When you consider the cost of redrawing them from scratch, most companies find that it is a lot more economical to have them converted.  Plus, using an experienced CAD conversion service will enable to have the files saved in the CAD format and layering method of your choice.  A reliable conversion firm will be able to support most CAD programs.  While there are software packages that can perform raster to vector conversion, there are usually many issues with the converted file that require fixing, so this is another reason to stick with a professional.

Advantages of Raster to Vector Conversion for Renovations


Usually, the drawings that architects, engineers, and contractors are handed for renovation work are “As-built drawings” or “record drawings.”  These types of drawings are very important because they show exactly how the original contractor built the project and what changes were made during the construction process. Transferring the revisions and completing the markups on the original drawings should have been executed carefully for the final as-built set of drawings. However, this is not always the case, and some of the final as-built drawings that are on the record will not contain all of the current modifications that exist, especially if modifications were made, and not recorded after the initial construction was completed.

Therefore, details provided by a visual inspection of the property, and electronic measurements can be added to the converted vector file in order to obtain a truly accurate CAD drawing.  The advantages of conversion from paper drawings to digital CAD drawings are:Advantages of Raster to Vector Conversion for Renovations

  • Most municipalities and government agencies require all plans submitted for review to be presented in a digital format, and this goes for renovation and revitalization programs, not just new construction.
  • The CAD drawings will reflect all modifications made to the building over the years, plus the new changes required for the renovation.
  • The architects, engineers, and contractors involved in the project will be able to easily retrieve the drawings from the current digital database of electronically generated prints.
  • Integrate an engineering change order (ECO) into the renovation process is much easier with a CAD file than with a hand-drawn document.
  • The final “as-built” drawings of the renovation can become a permanent “record drawing” that can easily be accessed and updated for future changes or renovations.

White paper: 3 Strategies for optimizing your paper to CAD Conversion

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