Geoscience Reference
In-Depth Information
ponds to the 5 cm interval equivalent to the
sqrt((y(2,1)-y(1,1))^2+(x(2,1)
-x(1,1))^2)
pixels gathered using
ginput
.
ix = 5 * size(I,2) / sqrt((y(2,1)-y(1,1))^2+(x(2,1)-x(1,1))^2);
iy = 5 * size(I,1) / sqrt((y(2,1)-y(1,1))^2+(x(2,1)-x(1,1))^2);
We can now display the image using the new coordinate system where
ix
and
iy
are the width and height of the image, respectively (in centimeters).
imshow(I,'XData',[0 ix],'YData',[0 iy]), axis on
xlabel('Centimeters'), ylabel('Centimeters')
We now digitize the color-intensity transect from the top of the image to
bottom. h e function
improfile
determines the RGB pixel values
C
along line
segments dei ned by the coordinates
[CX,CY]
.
[CX,CY,C] = improfile;
h e scaled image and the polygon are displayed in the same i gure window.
h e three color-intensity curves are plotted in a separate window.
imshow(I,'XData',[0 ix],'YData',[0 iy]), hold on
plot(CX,CY), hold off
figure
plot(CY,C(:,1),'r',CY,C(:,2),'g',CY,C(:,3),'b')
xlabel('Centimeters'), ylabel('Intensity')
h e image and the color-intensity proi les are on a centimeter scale. To detect
the interannual precipitation variability, as recorded in the color intensity of
the sediments, we need to convert the length scale to a time scale. We use the
22 white diatomite layers as time markers to dei ne individual years in the
sedimentary history. We again use
ginput
to mark the diatomite layers from
top to bottom along the color-intensity transect and store the coordinates of
the laminae in the new variable
laminae
.
imshow(I,'XData',[0 ix],'YData',[0 iy]), hold on
plot(CX,CY), hold off
laminae = ginput;
To inspect the quality of the age model we plot the image, together with the
polygon and the marked diatomite layers.
imshow(I,'XData',[0 ix],'YData',[0 iy])
hold on
plot(CX,CY)
plot(laminae(:,1),laminae(:,2),'ro')
xlabel('Centimeters'), ylabel('Centimeters')
hold off