Feature Request: Measure based on a scale

[Booma-Booma]

I frequently have to measure engineering drawings that are not to scale. They do have dimensions markers on them with listed values. I have to take a ruler and measure that line. Since I know what the length of the line is supposed to be and what it actually is measured to I can use that as a scale factor/ratio (known value divided by the measured value) . I can then measure any other distance on that image and multiple it by the scale factor to determine what it should be.

I know there are problems with this method, particularly if the aspect ratio is different from the original. It would still make for a pretty good approximation. I believe this would be a valuable addition to the ScreenShot Captor set of tools. I see the process working like:
1. Take a screen capture
2. use a "caliper" tool to identify a known length on an image. Enter in the corresponding known length
3. use a calibrated measure tool to select two points on the image - the calibrated length will be displayed.

It really doesn't have to be much more sophisticated than that. Maybe there could be an option to apply a horizontal and vertical calipers to attempt to correct for aspect ratio errors?

Thanks,
Troy

[wraith808]

Not free, but this does help with what you ask.

http://www.iconico.com/caliper/

[Booma-Booma]

Hi Wraith808,

Thanks for the link I'll take a look.

[mouser]

Iconico's caliper has been mentioned before.  Surely there have to be some free tools that do that too?

[tomos]

This is something I would be interested in as well.

I was going to say this:

But in my case I would need to zoom in to measure some things: I presume that because the image now has a different 'screen scale', the scalebar will have to be measured again. Or am I misunderstanding there?

but see Iconico seem to have that covered -- in PDF, at any rate:

• Adobe Acrobat plug-in, measure PDFs as you zoom in and out

If needing zoom and using graphics programmes (I usually am), it's probably not much more difficult to have the page rulers in, say metric, and then measure each relevant length and multiply each by the scale factor. This would then be the same no matter what the zoom.

[Booma-Booma]

I have looked around at the available tools and I haven't seen anything that I am interested in. I think the ones that mimic actually calipers are far to bulky for my tastes - you have to move it around and rotate it. I would rather just click two points and get an estimate. That is why I thought I would ask about it here. I think it would be perfect for screenshot captor. I use it every day.

Presumably, if the user selected two points to define a line, you would then know how many pixels make up that line (roughly). The user would assign a length to that measurement. That would assign a scale factor at that zoom level. So any other lines drawn could have a measurement associated with it. I know this works because that is what I do by hand with printed engineering drawings. I'd be very happy with this functionality.

I would only want to zoom in to better define either end point of a line, making sure that it lined up as closely as possible with the feature that I want a measurement estimate from.