inserting os map download to drawings

[dano200]

Hi,

 

I draw in model space at 1mm dimensions at 1:1. I also download os maps that are at a scale of 1/1250, 1/200 or 1/500, when i scan these and insert them into the model space (so that I can intergrate them into my drawings) they are so small I cannot use them.

 

is there a way of inserting these at a scale so that they are 1:1 like model space is?

 

I hope this makes sense..... what I need to do is have the os site plans at the same scale as my house layouts so I can plot my layouts onto the os plots.

 

Thanks in advance

 

Daniel

[eldon]

The easiest way to get OS plans to scale is to buy them. You can get DXF extracts that use a scale of metres, and probably only costs £40.00 or so for a building site.

 

If you are doing it the illegal way by scanning them, then you will have to scale them up to suit. Be warned that OS maps are not surveyed for a scale to be building houses, and the boundaries may not be where shown. To make sure of the boundaries, you will have to get a topographic survey - it is the only way.

 

At the moment, there is no free access to OS survey data.

[dano200]

The easiest way to get OS plans to scale is to buy them. You can get DXF extracts that use a scale of metres, and probably only costs £40.00 or so for a building site.

 

If you are doing it the illegal way by scanning them, then you will have to scale them up to suit. Be warned that OS maps are not surveyed for a scale to be building houses, and the boundaries may not be where shown. To make sure of the boundaries, you will have to get a topographic survey - it is the only way.

 

At the moment, there is no free access to OS survey data.

 

 

 

Hi,

 

yes I buy the maps, I use them for basic planning applications just need to know how I get them into the model area at the same scale I am working in.

 

regards

 

Daniel

[eldon]

If you bought the maps, then I am bewildered at this talk of scanning them. Why not buy the DXF version in the first place?

 

I have yet to find an accurate way of turning a scanned image into a scaled image. If you have some known lengths, then you could use Align. But if you haven't got a topographical survey, then you won't have any known lengths.

 

Ordnance Survey admit to using generalisation in mapping, so the features that you need may not be there.

 

For accuracy, go the DXF route. As soon as mapping gets on to paper, there is danger of distortion.

[dano200]

hi,

 

I have the same problem if I buy the dxf file, when inserted into model space they are tiny.

 

ok, if I buy a dxf map at say 1:200 is there a way if inserting this into model space at 1:1?

 

regards

 

Daniel

[eldon]

The OS DXF file is in metre units, and to Ordnance Survey coordinates.

 

If you must work in mm, then you will have to scale it up by 1000 times. Have you never bothered to check a distance on the scale bar included with all DXF files? That should tell you that basic drawing unit is metres. You cannot buy a scaled DXF file from the OS. It is always supplied at 1 to 1 in metre units.

[dano200]

ok, I will go and search how to scale up

[eldon]

It is not clear as to how you get the DXF file into your drawing.

 

Do not go the DXFIN method. There is no facility for scaling, and because the coordinates are Ordnance Survey coordinates, the image may end up several hundred miles from your area of interest!

 

First open up the DXF file (in the Open file dialogue box, go down to the bottom and choose Files of type DXF). Zoom extents, so that the mapping is on the screen. Then using the command Base, make the base point on the mapping. Then save it as a drawing, and close it. Now when you have opened up your drawing, use the Insert command, and you then have the facility for scaling. Enter 1000 in the X, Y and Z scaling, and the drawing is now on the end of your cursor for you to pick an insertion point. If you leave it unexploded, you can now align it to suit your drawing, by moving and rotating it. Do not do any more scaling at this stage, because that would destroy the accuracy of the mapping.