[GIS算法] DEM相关处理 - 窗口分析（以平均值为例）| 裁剪 - C语言实现

版权声明：本文为博主原创文章，若有错误之处望大家批评指正！转载需附上原文链接，谢谢！ https://blog.csdn.net/summer_dew/article/details/83993950

#include<stdio.h>
#include<stdlib.h>

typedef struct{
	double x0,y0; //左下角点的坐标值
	int dx,dy; //栅格单元大小
	int ycount,xcount; //行列号
	double **M; //矩阵
}DEM;

DEM* CreateDEM(int xcount,int ycount); //创建DEM
int InitDEM(DEM *pDEM); //初始化DEM
void PrintDEM(DEM dem); //输出

DEM* SubDEM(DEM dem, int row, int col, int nrow, int ncol); //裁剪
DEM* WindowAnalysis_Mean(DEM dem, int size); //窗口分析


/*测试数据
5 5
1 3 5 2 0
4 3 8 3 4
8 5 0 6 3
2 1 3 5 6
9 7 2 4 1
*/
int main() {
	DEM *pDEM, *pMean;
	int xcount,ycount;

	printf("输入行列数：\n>>> ");
	scanf("%d%d", &xcount, &ycount);
	pDEM = CreateDEM(xcount, ycount); //创建DEM
	InitDEM(pDEM); //初始化
	PrintDEM(*pDEM); //输出
	printf("\n");

	pMean = WindowAnalysis_Mean(*pDEM, 3); //3x3窗口分析求平均值
	PrintDEM(*pMean);

	return 0;
}

DEM* CreateDEM(int xcount, int ycount) {
	DEM *p;
	int i;
	p = (DEM *)malloc(sizeof(DEM)); if (!p) exit(0);
	p->xcount=xcount;p->ycount=ycount;
	p->M = (double **)malloc(sizeof(double *)*xcount); if (!p->M) exit(0);
	for (i=0; i<xcount; i++) {
		p->M[i] = (double *)malloc(sizeof(double)*ycount);
		if (!p->M[i]) exit(0);
	}
	return p;
}
int InitDEM(DEM *pDEM) {
	int i,j;
	printf("以矩阵的形式输入DEM的值：\n");
	for (i=0; i<pDEM->xcount; i++) {
		for (j=0; j<pDEM->ycount; j++) {
			scanf("%lf", &pDEM->M[i][j]);
		}
	}
	return 1;
}
DEM* SubDEM(DEM dem, int row, int col, int nrow, int ncol) {
	DEM *sub;
	int i,j;

	if (row+nrow>dem.xcount || col+ncol>dem.ycount || row>dem.xcount || col>dem.ycount) return NULL;

	sub = CreateDEM(nrow, ncol);
	for (i=0; i<nrow; i++) {
		for (j=0; j<ncol; j++) {
			sub->M[i][j] = dem.M[i+row][j+col];
		}
	}

	return sub;
}
void PrintDEM(DEM dem) {
	int i,j;

	for (i=0; i<dem.xcount; i++) {
		for (j=0; j<dem.ycount; j++) {
			printf("%lf\t", dem.M[i][j]);
		}
		printf("\n");
	}
}
DEM* WindowAnalysis_Mean(DEM dem, int size) {
	// size:窗口大小
	// 例如：3X3的窗口 size=3
	DEM *mean;
	int i,j;
	int x,y;
	int step;
	int x_step, y_step;
	int flag;
	double sum;

	mean = CreateDEM(dem.xcount, dem.ycount);
	for (i=0; i<mean->xcount; i++) {
		for (j=0; j<mean->ycount; j++) {
			sum = 0; //窗口的总和
			step = size/2; //位移量
			flag = 0; //是否越界
			// 计算窗口的sum
			for (x_step=-step; x_step<=step && !flag; x_step++) {
				for (y_step=-step; y_step<=step && !flag; y_step++) {
					x = i+x_step;
					y = j+y_step;
					if (x<0 || y<0 || x>=mean->xcount || y>=mean->ycount) { //越界
						flag = 1; //越界
					} else { //没有越界
						sum += dem.M[x][y];
					}
				}
			}
			//赋值
			if (flag) { //越界了
				mean->M[i][j] = dem.M[i][j];
			} else { //没有越界
				mean->M[i][j] = sum/(size*size);
			}
		}
	}
	return mean;
}