Arrow field Tool. 4-25-01
Draws arrows on an image, to represent a vector field, where the field is given as a magnitude image and a direction image. Magnitude and direction images should have the same dimensions as the image on which the arrows are drawn.
Buttons
Magn Im! Set front image to be the source of magnitude values.
(Click on the magnitude image, then click this button.)
Dir Im! Set front image to be the source of direction values.
Draw Im! Set front image to be where arrows are drawn.
Stress arrow color! Set color of type in this button and the color
for drawing stress arrows to be the color of
'***Buttons*** / Pick Color'
Crack arrow color! Set color of type in this button and the color
for drawing crack arrows to be the color of
'***Buttons*** / Pick Color'
Arrow Inc Set the number of pixels between arrows, both
horizontally and vertically.
Arrow Length Xf Set the scale factor for the arrow length.
Length (pixels) = mag im value * this factor.
Arrow Heads! Toggles between yes and no. For values such as
stress that are 'bi directional', use 'no'.
Draw Arrows! Draws field of arrows onto the 'Draw Im'
Buttons! Pops the main image button window.
Hints! Displays this file.
Example directions - displaying stress field
1) Load the microstructure image on which arrows are to be drawn.
If image is in a text file (see below), then the dimensions must first
be known. See
'***Buttons*** / File / Info & other formats / Hints / ASCII'
for directions on loading this type of file.
Otherwise, just open the file (gif, jpeg, tiff).
2) Expand the image to full size if desired: '***Buttons*** / <->!'
3) Load the magnitude and direction images.
If image is in a text file (see below), then the dimensions must first
be known. Click on the microstructure image and then
'***Buttons*** / Info!' to see the image dimensions.
See
'***Buttons*** / File / Info & other formats / Hints / ASCII'
for directions on loading this type of file.
4) Resize the images as desired by clicking on each in turn, then
clicking '<->!'.
5) If the images are transposed with respect to the microstructure
image, use '***Buttons*** / Adjust / Transpose', and 'Yes' to close
the original images, to fix them.
6) Click on the magnitude image, then on '*Arrow Field* / Mag Im!'.
Do the same for the magnitude and draw images.
7) Set the parameters
Arrow Inc the greater the number, the wider the spaces
between arrows.
Arrow Length Xf The greater the value, the longer the arrows.
Arrow Head size. The heads are a constant size. The greater
the value, the larger the heads.
Use zero for no heads.
8) Draw the arrows using 'Draw / ...' Note that the drawing is
temporary. To save images with arrows, use a screen grab. To erase
the arrows, use '***Buttons*** / Redraw!'.
ASCII file formats
microstructure image ASCII file
Sample file name: microstructure.dat --
One integer per line. Symbol indicating type of material.
Sample lines from file:
...
1
1
2
2
...
1 matrix
2 rocks
3 pores
4 effective material (should not have any of these).
---------------------------------
Stress image ASCII file
The stress images are in one ASCII text file, one pixel per line.
Note that the image dimensions are not in the file and must be
input by hand using:
***Buttons*** / File / Info & other formats / ASCII / set dimensions
Zeros are for compressive stress and for pores.
Sample lines from the file:
magnitude angle (radians)
...
0.00000000 0.00000000
2.56360338 -0.13914777
1.72512885 -0.13432072
...
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