grid marking photos

Re-reading a much earlier post about laying underfloor heating pipes, the author suggests photographing the layout prior to screeding with a

500mm grid for future reference.

Obviously one could mark up a batten but is there any cleverer way?

Reply to
Tim Lamb
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ISTR seeing archaeologists marking out grids with tape.

Colin Bignell

Reply to
Nightjar

I fixed a fabric (dress makers) measuring tape under some rafters in a bay window and photographed it - so I had a reference of both the rafter layout (non regular) and conduit for after I plasterboarded it.

In this case, just lay a steel tape over the floor in both axis and photograph well enough to be able to ready the tape (you'd be surprised how well a hires digital photo will zoom if the light is right and the hand was steady).

Probably need several photos - say 4 quarters - but that works well enough in the end.

Reply to
Tim Watts

Yep, you need a full grid as you don't really know how prespective is going to distort the grid in the photograph.

White cotten string?

Reply to
Dave Liquorice

Umm.. I always take site photos at every opportunity. Usually you can estimate the location of a buried object by measuring from things that remain visible.

I just idly wondered if there could be some gizmo built in to the camera electronics to create a graticule effect. CD graphics have been around for years and it felt do-able:-)

Probably shows how little I understand about photo software:-) Fix the location of a couple of convenient pixels and have everything else located.

Reply to
Tim Lamb

A tin of beans here, a coach bolt there, a 380ml cart there... ok if you dont need much grid resolution.

NT

Reply to
meow2222

Putting a square grid on would be a POP. Putting a grid on a single image that matched the prespective would not be so easy. These days with X Y Z position sensors knowing the camera orientation is easy, I think all you need then is camera height above the floor.

Take multiple photos moving a foot or so between each one and software these days can look at those, pick out key points, cross match those points across the image set and build a 3D model for you ... Not in camera (yet!) though.

Reply to
Dave Liquorice

Actually... If you put 4 markers on the floor at the corners of a square, it is trivial in Gimp to do a "perspective correction". This overlays a grid on the image that you stretch and line up with known markers (your 4 floor markers in this case).

Gimp will then linearly transform your image to match.

Reply to
Tim Watts

Seconded. I have used this to take a photo of a poster or picture hanging on a wall, but from a steep sideways angle, and GIMP simply straightens it all out and makes it look as though the camera was directly in front when the picture was taken. GIMP is very powerful, just not always intuitive; but this function is easy to use, just drag the corners to where you want them.

I had a similar, but simpler, problem some years ago; the water stopcock outside was in a tube located out in my front lawn, and I just measured where it was from the garden path edge, and from the pavement edge. So when it got covered up as the grass grew etc, it was easy to find it again when required.

Reply to
Davey

Ah! Don't know Gimp. I have Photoshop elements 7 but don't claim any expertise:-)

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Reply to
Tim Lamb

I have GIMP somewhere but haven't got over the vertical learning curve. B-)

Reply to
Dave Liquorice

Non-photographic approach... Place some of these in strategic positions:

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Reply to
Richard

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