calc_area.py

import cv2
import numpy as np


def afforestation_area():
    
    img = cv2.imread('map.png')
    shifted = cv2.pyrMeanShiftFiltering(img,7,30)
    gray = cv2.cvtColor(shifted, cv2.COLOR_BGR2GRAY)
    ret, thresh = cv2.threshold(gray, 0, 255,cv2.THRESH_BINARY | cv2.THRESH_OTSU)
    hsv = cv2.cvtColor(shifted,cv2.COLOR_BGR2HSV)

    lower_trees = np.array([10,0,10])
    higher_trees = np.array([180,180,75])

    lower_houses = np.array([90,10,100])
    higher_houses = np.array([255,255,255])

    lower_roads = np.array([90,10,100])
    higher_roads = np.array([100,100,100])

    lower_feilds = np.array([0,20,100])
    higher_feilds = np.array([50,255,255])

    lower_feilds_blue = np.array([0,80,100])
    higher_feilds_blue = np.array([255,250,255])


    masktree = cv2.inRange(hsv,lower_trees,higher_trees)
    maskhouses = cv2.inRange(hsv,lower_houses,higher_houses)
    maskroads = cv2.inRange(hsv,lower_roads,higher_roads)
    maskfeilds_houses = cv2.inRange(hsv,lower_feilds,higher_feilds)
    blue_limiter = cv2.inRange(hsv,lower_feilds_blue,higher_feilds_blue)
    maskfeilds = maskfeilds_houses
    res = cv2.bitwise_and(img,img,mask=maskfeilds)

    print(res.shape) # (640, 622, 3)
    print(np.count_nonzero(res)) # 679089

    print("number of pixels", res.size//3)
    tot_pixels = res.size//3
    # print("number of pixels: row x col", res.)

    no_of_non_zero_pixels_rgb =  np.count_nonzero(res)
    row, col, channels = res.shape # 152886
    print("percentage of free land : ", (no_of_non_zero_pixels_rgb/(row*col*channels))) # 0.5686369573954984
    percentage_of_land = no_of_non_zero_pixels_rgb/(row*col*channels)

    # https://www.unitconverters.net/typography/centimeter-to-pixel-x.htm
    # says 1 cm = 37.795275591 pixels
    cm_2_pixel = 37.795275591
    print("row in cm ", row/cm_2_pixel)
    print("col in cm ", col/cm_2_pixel)

    row_cm = row/cm_2_pixel
    col_cm = col/cm_2_pixel
    tot_area_cm = tot_pixels/(row_cm*col_cm)
    tot_area_cm_land = tot_area_cm*percentage_of_land

    print("Total area in cm^2 : ", tot_area_cm_land)

    # in google maps 2.2cm = 50m => 1cm = 22.727272727272727 m in real life at zoom 18
    # 1cm^2 = (22.727272727272727m)^2 = 516.5289256198347 m^2
    print("Total area in m^2 : ", tot_area_cm_land*(516.5289256198347))
    tot_area_m_actual_land = tot_area_cm_land*(516.5289256198347)

    # 1 m^2 = 0.000247105 acres :: source Google
    tot_area_acre_land = tot_area_m_actual_land*0.000247105
    print("Total area in acres : ", tot_area_acre_land)

    # https://www.treeplantation.com/tree-spacing-calculator.html
    # says if you have 2 ft between rows, and 2ft between trees will can take 10890 trees per acre.

    number_of_trees = tot_area_acre_land*10890
    print(f"{round(number_of_trees)} number of trees can be planted in {tot_area_acre_land} acres.")
    
    return tot_area_acre_land, round(number_of_trees)

    # show the output image
    # cv2.imshow('res',res)

    #cv2.imshow('mask',maskfeilds)
    # cv2.imshow('img', img)


    #cv2.imshow("hsv", hsv)
    # cv2.waitKey(delay=0)
    # cv2.destroyAllWindows()

# afforestation_area()