Photo to DXF conversion

[farjoe]

Hi,

I have a photo of the cut plywood panels of a small stitch and glue boat taken at an angle of about 45^ to the floor.

It is fairly easy to construct approximate edge curves of these panels in most cad packages.

I wonder if there is a way to actually transform this drawing into the approximate top view of these panels.

regards

[Raggi_Thor]

You need some reference points or lines or agrid in the photo. Then you can distort the drawing in a cad program so it matches the references.

[ludesign]

Originally Posted by farjoe

Hi,

I have a photo of the cut plywood panels of a small stitch and glue boat taken at an angle of about 45^ to the floor.

It is fairly easy to construct approximate edge curves of these panels in most cad packages.

I wonder if there is a way to actually transform this drawing into the approximate top view of these panels.

regards

It would be possible in TouchCAD, though it would take a little tweaking and you need have some sort of measurements to import the image in exact scale relative to the 3D model.

Fixing the perspective can easily be done with the built in tools in the background image import dialog.

I would then trace the panels and unfold them together with an estimated 3D model of the same model. I would make use of the dynamic link between the 3D model and the unfolded pattern, where I would select one or several control points in 3D and then nudge them in the Unfold view to directly see how the unfolded pattern changes in realtime.

[farjoe]

Originally Posted by ludesign

Fixing the perspective can easily be done with the built in tools in the background image import dialog.

I don't have Touchcad so I am unsure what commands you are using to do the above. Perhaps you could amplify?

As far as dimensioning goes there is at least one dimension which is known and that is the length of the plywood panel which is obviously 8ft.

[Raggi_Thor]

If you have a picture of a sheet of plywood with known dimensions, say 4x8 or 1220x2440, you can (in some programs) distort your image to match the points you know. Another way to do it would be to draw a rectangle with correct dimensions and the rotate then image plane (in 3D) to get the right view. Not very accurate, but maybe good enough.

Can you show us the picture?

[ludesign]

This is just a simulation done in TouchCAD 3.5. I generated an image at fairly low resolution, about 1000 x 700 pixels, to see what kind of errors I would get. I then generated a simulated distorsion (1), which I imported and fixed the perspective in the TouchCAD background image dialog. I then traced it (3) in scale and placed it on top of the original (4). Despite not trying very hard I still had an average error of about 1 mm and at no point worse than 4 mm.

[farjoe]

Originally Posted by Raggi_Thor

Can you show us the picture?

Raggi,

the picture is available on the net and the design is being offered for sale. I therefore do not know if it is ethical to show the picture since it might be construed as an attempt to 'hacking' the design.

My intention is purely educational and I personally think it would be impossible to get anywhere near to the design from this photo.

regards

[Zooarch]

We use a nifty program called Photomolder. You can take a series of photos or use just one, mark points in the photo and the software will export this as a DXF drawing. It works very well and can be very accurate.

You can download a working version to try out. Go to www.photomodeler.com

[nero]

Note: You have not even bought TouchCad and the company is giving you excellent tech and training support. This type of service doesn't stop even after you purchase!

Also, there is a straight forward solution for about any design need.

No, I do not own stock or get a percentage of sales. smile