A4 - Area estimation of images with defined edges

PART I: Analytic measurement vs. Green's method for obtaining the area of regular geometric shapes

The analytic measurements are obtained using the formulas for area:

* square: length x width (in pixels)
* circle: pi x (radius squared)

The area using Green's method on the other hand is obtained using the formula:
The figures below are the black and white images of the geometric shapes used. These are made using the scilab code done for activity 2.

Square
Width: 200 pixels
Height: 200 pixels
Analytic measurement: 4000 pixels
Area using the Green's method: 40000 pixels
% difference: 0

Figure 1: Black and White Square

Figure 2: Plot of Square Edge Pixels

Circle
Radius: 104.99 pixels
Analytic measurement: 34636 pixels
Area using the Green's method: 34034 pixels
% difference: 1.74

Figure 3: Black and white Circle with radius

Figure 4: Plot of circle edge pixels

Circle
Radius: 75 pixels
Analytic measurement: 17671.46 pixels
Area using the Green's method: 17350
% difference: 1.82

Figure 5: Black and white Circle with radius

Figure 6: Plot of circle edge pixels

Circle
Radius: 45 pixels
Analytic measurement: 6361.73 pixels
Area using the Green's method: 6201 pixels
% difference: 2.53

Figure 7: Black and white Circle with radius

Figure 8: Plot of circle edge pixels

Using Scilab's function follow and Green's method, the area of regular geometric shapes (square and circles with different radii) are determinded. The % difference between the two methods are relatively small. As observed above, we can say that as the radius of the circle becomes smaller, the % difference between the two methods increases.


PART 2: Finding the lot area using a map image

I have chosen to use the map of UPLB, particularly the lower grounds of Freedom Park.

Figure 10: Map of UPLB's Freedom Park

source: http://www.nationsonline.org/oneworld/map/google_map_philippines.htm


To obtain the figure below, the following image processing techniques were used:
1. Using GIMP, select the place which you want to determine the area of.
2. Fill the background with black, and the selected area with white (binarize it :))

LAND AREA:
conversion factor: 84 pixels = 100m
Analytic area: 20619.17 pixels
Green's method: 20602.5 pixels
% different: 0.08

Figure 11: Black and white image of the land

Figure 11: Plot of edge pixels

Thank you to Rap-rap for helping me with this activity! :D

I would like to give myself a grade of 10 for this activity.