Need to overlay two images

M
Posted By
mcgrath
Feb 9, 2006
Views
1030
Replies
5
Status
Closed
I have two scanned images (usually tif images)of maps at different linear scales; a flood map (typically 1"=2000′) and a parcel map of differing scales. What I want to do is overlay them and adjust one image up or down proportionatly to match the other image. Both images have section lines that will make it easy to align.

More than likely the flood map would be made transparent to look like a

watermark over the parcel map. I have to do this operation some days 20-30 times and waste TONS of paper at a copier resizing one of the maps a few times, then using a light table draw the parcel lines over the flood image.

I am serious, if I could find a program to do this, I would typically save a ream of copy paper a week minimum (and copier toner to boot!).

Please help!, Thanks

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D
Done
Feb 9, 2006
wrote in message
I have two scanned images (usually tif images)of maps at different linear scales; a flood map (typically 1"=2000′) and a parcel map of differing scales. What I want to do is overlay them and adjust one image up or down proportionatly to match the other image. Both images have section lines that will make it easy to align.

More than likely the flood map would be made transparent to look like a
watermark over the parcel map. I have to do this operation some days 20-30 times and waste TONS of paper at a copier resizing one of the maps a few times

It is trivial to do in Photoshop.
P
Pat
Feb 9, 2006
Not terrible difficult to do depending on your application.

First, if you need it for legal purposes, have your surveyor do it. It’s worth the money. Second, if you are doing it a lot, there are companies that banks use that will tell you if you are in a flood plain or not, but I don’t think they produce a map. Third, if you are doing it a lot, you might want to switch over to a GIS system and buy a map data set and to it there. That’s the easiest. Finally, check with your local planning office. They might have a GIS system on-line (or off-line that they will do it for you). That said, on to Photoshop. In fact, you can do this in PS Elements (which is cheaper if you haven’t bought PS yet)

Basically there are two things you have to do. First, get rid of white and make the proper alignment.

I would start by opening both maps. Go to the plot plan and hit Select>all Then Edit>Copy. Go to the Floodplain map and hit Edit>Paste. Now you have the floodplain map as your background and your plot plan as a layer. Select the layer so it active by hitting Select>All. Use the majic wand to select a white area and make that your selection. (make you are set to non-contiguous) Then hit delete. You are now left with just the black lines. This disadvantage of this is it might cut up angles and measurements, if you need to read them. Now click the Move Tool. You will notice a small box on each corner. Before you do anything, you will notice a small icon that looks sort of like a links of chain. Click that to keep your proportions. Now use the move tool by clicking on a corner and dragging the site to what you want. You can click the image to move it back and forth. Play with it until your registration is right. Save it. Print it.
D
Done
Feb 9, 2006
"Pat" wrote in message
Not terrible difficult to do depending on your application.
First, if you need it for legal purposes, have your surveyor do it. It’s worth the money. […]

Basically there are two things you have to do. First, get rid of white and make the proper alignment.

I would start by opening both maps. Go to the plot plan and hit Select>all Then Edit>Copy.

It is far better to drag the image from one open document to the other. It will go faster, and CS won’t thrash around under the overhead of the clipboard. Then close the image you no longer need.

[…] Use the majic wand to select a white area and make that your selection. (make you are set to non-contiguous) Then hit delete. You are now left with just the black lines. This disadvantage of this is it might cut up angles and measurements, if you need to read them.

Okay, if we aren’t going to use masks, then the Background or Magic Eraser might be a better idea.

Now click the Move Tool.

Better yet to use transftorm-scale, holding the shift key to keep proportions. (He said they were not in proportion).
P
Pat
Feb 9, 2006
That too would be fine.

One minor correction. He said they were not to the same scale, not in proportion. He need to keep them in proportion, as you said, so they will overlay. If they are not to proportion, then he will need to adjust them accordingly, but at the scale he seems to be working at, I don’t think he will have any issues due to different projections. If he does, he will have to "rubber sheet" them to get things to line up (basically by taking one out of proportion). But also, there isn’t enough detail on a floodplain map to cause too much trouble — especially when you consider that they are WAGs to start with. If he need a high level of detail or precise measurements, he will need to have his/her surveyor get some base elevations and draw it. But since he is doing it himself, it seems like having it exact isn’t too important.

A simpler, but uglier, way would be to lay the plot plan on top of the floodplain map and then set the layer’s transparency to something like 50%. Then move it around and set the scale.
J
jenelisepasceci
Feb 10, 2006
"Pat" wrote:

….
Select the layer so it active by hitting
Select>All. Use the majic wand to select a white area and make that your selection. (make you are set to non-contiguous) Then hit delete. You are now left with just the black lines. This disadvantage of this is it might cut up angles and measurements, …

Simply set the layer mode to multiply instead.

Peter

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