C语言计算DEM文件填方挖方体积

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

#define PIXEL_SIZE 30.0 // 像素大小 #define NO_DATA_VALUE -9999 // 无效像素值

int main() { FILE *fp_dem; char *filename = 'dem.tif'; int width, height, i, j; float *elevation; float fill_volume = 0.0, cut_volume = 0.0;

// 打开DEM.tif文件
fp_dem = fopen(filename, 'rb');
if (fp_dem == NULL) {
    printf('Error: cannot open file %s!

', filename); return 1; }

// 读取DEM.tif文件头信息
fseek(fp_dem, 0x12, SEEK_SET);
fread(&width, 4, 1, fp_dem);
fread(&height, 4, 1, fp_dem);

// 计算DEM.tif文件大小
fseek(fp_dem, 0, SEEK_END);
long filesize = ftell(fp_dem);
long datasize = filesize - 0x44;

// 分配内存空间
elevation = (float *)malloc(datasize);

// 读取DEM.tif数据
fseek(fp_dem, 0x44, SEEK_SET);
fread(elevation, sizeof(float), datasize/sizeof(float), fp_dem);

// 遍历像素值，计算填方和挖方的体积
for (i = 0; i < height; i++) {
    for (j = 0; j < width; j++) {
        float elev1 = elevation[i*width+j];
        if (elev1 == NO_DATA_VALUE) {
            continue;
        }
        float elev2 = NO_DATA_VALUE;
        if (i > 0) {
            elev2 = elevation[(i-1)*width+j];
            if (elev2 != NO_DATA_VALUE) {
                float diff = elev1 - elev2;
                if (diff > 0) {
                    cut_volume += diff * PIXEL_SIZE * PIXEL_SIZE;
                } else {
                    fill_volume += (-diff) * PIXEL_SIZE * PIXEL_SIZE;
                }
            }
        }
        if (i < height-1) {
            elev2 = elevation[(i+1)*width+j];
            if (elev2 != NO_DATA_VALUE) {
                float diff = elev1 - elev2;
                if (diff > 0) {
                    cut_volume += diff * PIXEL_SIZE * PIXEL_SIZE;
                } else {
                    fill_volume += (-diff) * PIXEL_SIZE * PIXEL_SIZE;
                }
            }
        }
        if (j > 0) {
            elev2 = elevation[i*width+j-1];
            if (elev2 != NO_DATA_VALUE) {
                float diff = elev1 - elev2;
                if (diff > 0) {
                    cut_volume += diff * PIXEL_SIZE * PIXEL_SIZE;
                } else {
                    fill_volume += (-diff) * PIXEL_SIZE * PIXEL_SIZE;
                }
            }
        }
        if (j < width-1) {
            elev2 = elevation[i*width+j+1];
            if (elev2 != NO_DATA_VALUE) {
                float diff = elev1 - elev2;
                if (diff > 0) {
                    cut_volume += diff * PIXEL_SIZE * PIXEL_SIZE;
                } else {
                    fill_volume += (-diff) * PIXEL_SIZE * PIXEL_SIZE;
                }
            }
        }
    }
}

// 输出结果
printf('Fill volume = %.2f m3\n', fill_volume);
printf('Cut volume = %.2f m3\n', cut_volume);

// 释放内存空间
free(elevation);

// 关闭文件
fclose(fp_dem);

return 0;

}

// invalid file size怎么改正内容：如果出现 'invalid file size' 的错误，可能是因为读取文件大小的方式不正确。可以尝试使用其他的读取文件大小的方法，比如：

// 1. 使用 fseek 和 ftell 函数获取文件大小：

fseek(fp_dem, 0, SEEK_END);
long filesize = ftell(fp_dem);

// 2. 使用 stat 函数获取文件大小：

#include <sys/stat.h>

struct stat st;
if (stat(filename, &st) == 0) {
    long filesize = st.st_size;
} else {
    printf('Error: cannot get file size!\n');
    return 1;
}

// 注意：第二种方法需要包含头文件 <sys/stat.h>。