topic Re: Scaling a Raster Image Step by Step in AutoCAD Forum

Scaling a Raster Image Step by Step

Anonymous — Fri, 26 Aug 2016 18:43:23 GMT

I work for a Landscape Design Company, and I have the hardest time scaling Raster Images.Here is how I do it, so if there is a step I'm doing wrong, please point it out for me.

1. Immageattach command

2. locate image to be inserted

3. leave specify on screen, scale, checked

4. create image into a block

I already have a Model plan drawing in my opened file that I need to scale the image to.I will be getting my X & Y dimensions from the Model drawing.

5. I take a distance measurement from my Model drawing for the X axis, and a distance from the same point in the Image, then I divide the two dimensions.

6. Scale command, select Raster Image, specify base point, which I select the upper right corner of the Image

7. R for Reference

8. Type in the calc I got from step 5

9. Now I do the same for Y, but instead of using the scale command I take the calc and multiply it by the Y scale I have in the properties

10. I enter that # into the Y scale in properties

The Image is now scaled, I move the Image to a point in the Model, and send the Image to the back for an Underlay

Then I rotate the Image to align with the Model drawing, ......but the Image is never to scale with the Drawing.

Any Help is much appreciated.Thanks

Re: Scaling a Raster Image Step by Step

john.vellek — Fri, 26 Aug 2016 18:49:56 GMT

Hi @Anonymous,

Welcome to the Autodesk Community!

If you can attach a sample drawing and image file I could go through your steps to see what can be improved upon.

I know that I wouldn't be taking out a calculator if I didn't have to 🙂

Re: Scaling a Raster Image Step by Step

Anonymous — Fri, 26 Aug 2016 18:57:16 GMT

Attached is the DWG and Raster Image

Re: Scaling a Raster Image Step by Step

john.vellek — Fri, 26 Aug 2016 19:25:17 GMT

Hi @Anonymous,

I made a Screencast video to show the way I would approach this - no measuring involved!

The first thing I did was to attach the image and scale it up by eye so it was "close" to the size of your drawing.

Then, i moved it to a point on the drawing that matched a point in the image.

Next I rotated the image by Reference. Once the image was aligned with the drawing I then scaled it by Reference.

Realize that while this is likely good enough in this case to work from, that the original image might be warped or stretched which will cause additional scaling issues.

I hope this helps.

Please select the Accept as Solution button if my post solves your issue or answers your question.

Re: Scaling a Raster Image Step by Step

Anonymous — Fri, 26 Aug 2016 19:25:53 GMT

I also have to mention we work in decimals.
UNITS

Re: Scaling a Raster Image Step by Step

Anonymous — Fri, 26 Aug 2016 19:27:10 GMT

Thankyou so much.I will try it this way.

Re: Scaling a Raster Image Step by Step

albionpjl — Fri, 26 Aug 2016 20:33:40 GMT

I have a different method.
I usually just drag and drop images into about the right place. If they were scanned at 100%, and if I have the scale inserted content setting set to metres (instead of unitless) (We work at 1 unit is 1 metre), the scale of the image is about right. (ie if the image is a 1 to 50 map, scanned at 100% then I import it and set the scale in properties to 50 and it's almost exactly right. )

Almost isn't quite good enough, so if it's an image that is to be aligned with a map or survey I use the align command. You click on a point on the image, the on the point on the map that it matches, then do the same for a second point, and enter. It asks if you want to rotate and scale and you click yes, and it automatically scales and rotates the image to fit those two points.

If there's nothing on the image that I can use for that, then I hope that it at least has a bar scale and I scale by that, using the scale-reference command.

Re: Scaling a Raster Image Step by Step

Anonymous — Fri, 26 Aug 2016 20:49:18 GMT

I've done the Align command.It comes close to what I need.I like that it rotates along with the command.One less step I need to do.Every 10 seconds I can shave off I'll take.