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authorWerner Almesberger <werner@almesberger.net>2014-09-15 19:19:09 (GMT)
committerWerner Almesberger <werner@almesberger.net>2014-09-15 19:19:09 (GMT)
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meme/README: very short description
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+Mesh measurement utility
+========================
+
+
+Usage:
+
+meme <path-to-STL-file>
+
+
+Mouse
+-----
+
+- move mouse: places the cursor on the vertex closes to the mouse pointer
+- turn scroll wheel:
+ - C key not held: zooms in or out
+ - C key held: increase/decrease contrast
+- click left button:
+ - not on measurement point: set/move measurement point
+ - on measurement point: cancel measurement point
+
+
+Keyboard
+--------
+
+- C: enter contrast enhancement mode, see below
+- G: toggle grid (edges) display
+- P: toggle profiles display, see below
+- Q: quit
+- *: center and zoom to extents
+
+
+Profiles
+--------
+
+Profiles show the intersections of the mesh with XZ and YZ planes placed
+at the cursor location. The XZ profile is shown at the bottom of the window
+(screen X is mesh X, screen Y is mesh Z) and the YZ profile is shown at
+the right side (screen -X is mesh Z, screen Y is mesh Y).
+
+Profiles are toggled with the P key.
+
+
+Contrast enhancement
+--------------------
+
+Contrast enhancement mode can be entered by pressing and holding the C
+key. When pressing C, the Z to greyscale mapping is adjusted such that
+the Z value at the cursor position becomes the middle of the greyscale
+range.
+
+Contrast can be increased or decreased with the scroll wheel. Areas
+that exceed the contrast range are shown in yellow.
+
+The normal mapping is restored when releasing the C key.
+
+
+Workflow
+--------
+
+- load the STL file, ideally at a resolution of 100 um or better
+- zoom into the area of interest
+
+To measure vertical distances:
+
+- use contrast enhancement mode to identity flat areas at the desired
+ heights and place the measurement markers there. When both markers
+ are present, a window with the measured distances will appear.
+
+To measure horizontal distances:
+
+- note that the meshes are not corrected for the size of the scanning
+ needle, which has a hemispherical tip with a diameter of 0.8 mm and
+ a conical shaft.
+
+- use profiles and/or contrast enhancement to find the desired edges.
+ Edges are typically located between the last point of a plateau and
+ the adjacent point that is slightly below the plateau.
+
+- left-click to place a measurement marker
+
+- find the corresponding second point and place the second measurement
+ marker
+
+To clear a marker, move the cursor exactly on the marker and
+left-click.
+
+
+Known bugs and limitations
+--------------------------
+
+- only suitable for 2.5 D scans, i.e., there it at most one vertex at
+ any (x, y) position
+- doesn't support other views than from the top
+- doesn't support rotation
+- profiles overwrite each other (clear artefacts caused by this by
+ zooming out and in again)