How to scale correctly when importing a PDF?

[Anonymous]

For example, if a PDF of a building states '1:100 @ A1', how am I able to scale this to fit 1:1 with an existing CAD library's blocks?

Thanks for any help anybody can provide.

[chriscowgill7373 · Accepted solution]

It depends on a few factors.  If the pdf when brought in at a scale of 1 is the actual paper size, in theory, you could scale it up 100 and it would then be 1:1.  This could be affected though if the pdf is scanned or from a reduced size print.

[ChicagoLooper]

You are dealing with a sheet sheet known as A1. This is an ISO sheet measuring 594mm X 841mm. When the sheet dimensions are converted to inches, it is 23.39" X 33". Do not confuse sheet A1 with ANSI-D (22" X 34") or Arch-D (24" X 36"), the A1 sheet is a size all its own.

Based on your sheet size, your 1:100 scaled PDF probably has drawing(s) at 1 meter:100 meter or

1-meter modelspace drawing units = 100-meter paperspace units

But.........it could also be 

1-mm modelspace drawing units =  100-mm paperspace units

If a scale bar is shown on the PDF, then scale according to the scale bar. If no scale bar is present then here are three possible scenarios.

Scenario 1:

Scale the actual sheet that you have inserted to be width=594 and length=841.

Scenario 2:

If your drawing is using imperial units of feet, then you'll need to convert the 594 X 841 into feet using the appropriate factor.

Scenario 3:

If your drawing is using imperial units of inches, then you'll need to convert 594 X 841 into inches using the  appropriate factor. 

[Anonymous · Accepted solution]

I like to use the scale reference command, you pick two endpoints of a line that has a dimension to it on the pdf and then enter that distance to scale the pdf.  It may not be exactly correct but sometimes it's close enough to get what you need. Kinda the same principle as stated before but I don't trust the scaling of a pdf.

[Anonymous]

Thanks for the detailed response. Unfortunately, there is no scale bar available which is why I'm having difficulties scaling the PDF accurately.

If I scale to 594 x 841mm, the drawing is far too small for the CAD components I'm using, which are all in mm and actual size. I've tried scaling the sheet to 59400 x 84100mm, which seems like it could fit, but I can't tell if this is the correct way to do it or simply a fluke?

The sheet also states '1:200 @ A3'. Based on A3 being 296x420mm, if I were to multiply these by 200, it would be 59400x84000mm - so almost the same. Am I on the right tracks here or missing the point?

[Anonymous]

Thanks for the response. I believe the PDF has been exported from AutoCAD and is a standard size. I can't seem to find the size in mm under properties/Get Info (I'm using a Mac).

When I insert the PDF and set the scale to 100, it still comes out far smaller than 1:1 with the CAD blocks I am using.

[Anonymous]

Thanks for the response, and yes this is what I have been using up until now. Unfortunately, I've been given a PDF without a scale bar, so am finally needing to figure out how to work only on scale information! (e.g. '1:100 @ A1')

[chriscowgill7373]

Are you able to share the pdf, or perhaps screenshots of what you are seeing?  Is there an item that is dimensioned to a known length? You could use that to scale it.  If for some reason you are going from metric to imperial, the scale may require a factor of 2540 or a factor of 12 if somehow it needs to get to feet from inches.  Without seeing the file, all we can do is guess and throw unit scales at it

[Anonymous]

Here is a screenshot of what I have been sent, although I have covered over certain parts for client confidentiality. There was nothing else in terms of a dimension, scale or mention of measurement units than what is shown in the screenshot. Do you have any further suggestions? Thanks for your help so far.

[vinodkl]

Hi,

Try this.

After importing the PDF, scale the imported PDF with scale 100 and then again with scale factor of 25.4

Is it any better now?

[chriscowgill7373]

Do you know the column spacing, you could use that to scale it.  Are you able to contact whomever created the drawing?  Other than that, I'm out of ideas.  It is unfortunate that there isnt much else provided for the scale.

[ChicagoLooper]

This is not sheet size A1. It has been cropped. You will need to upload the entire full size sheet without scaling the sheet to be bigger or smaller. 

[Anonymous]

Since its a building get the actual size of the building and scale one side of the building to that length

[Anonymous]

Yes, this seems like it could be right! The PDF sheet on AutoCAD comes out as 59400 x 84100, which is the same ratio as an A1 sheet (594x841mm) - so I'm guessing this is correct? It also seems to fit well with the CAD blocks I'm using. Where does the second scale factor '25.4' come from?

Thanks for your help.

[vinodkl]

Hi,

"25.4" is nothing but a conversion scale from mm to inches, as 1 inch=25.4 mm.