Measure Tool

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Marpel
Posts: 692
Joined: September 13th, 2009, 3:19 pm
What is the make/model of your primary camera?: Nikon D810
Location: Port Coquitlam, British Columbia

Measure Tool

Post by Marpel »

Tried to use the line and angle aspects of this tool.

But confused as to what the measurement actually represents. The length as displayed does not represent the length of an object within the image (as expected), and it does not appear to reflect the length of the line, compared to a ruler held up to the screen (and this changes when zoomed in/out). Does the dpi of an image have any relation to this measurement?

And, if I use the "snap to" button in the measurement option, then, without releasing that button, choose the angle option, the left side of the segment can be moved to any angle, but the right side snaps to only horizontal, 135, or vertical, although the Help file suggests the "snap to" does not work with angles. Is this correct?

Having said that, if the "snap to" function is not intended to work with angles, I also found that if a segment (let's say left side) is moved off horizontal to measure an angle, then I try to replace the left side to horizontal, I cannot get it to perfectly horizontal, even if I zoom in to make sure the line is perfectly flat and has no stair-stepping visible. It is out a, albeit VERY, minor amount. Just my OCD I guess. It would be nice to be able to "snap to" vertical and horizontal for either segment, to be able to check the angle of a building etc off vertical or horizontal after moving the segments from horizontal, rather than trying to visually get it to horiz./vert.

Marv
jsachs
Posts: 4203
Joined: January 22nd, 2009, 11:03 pm

Re: Measure Tool

Post by jsachs »

The measure tool measures the length of a line segment, similar to placing a ruler on a photograph. You can measure either in pixels or in physical units based on the dpi of the image. There is no way to measure the length of the actual object being photographed.

If Measure is set to Line, if the Snap button is depressed (it works like a toggle each time you click and release it), the angle is snapped to a multiple of 45 degrees so you can always create a vertical, horizontal or diagonal line segment. You can drag either end of the line segment by dragging the control points or drag the entire line segment by Shift-dragging. The slope angle of the line segment is shown in the Angle readout.

If Measure is set to Angle, there is no Snap button since you are measuring the angle between two line segments.
Jonathan Sachs
Digital Light & Color
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