pc.cc

// cloud must be sorted beforehand

size_t num_rows = 10;
size_t num_cols = 10;

size_t min_x = … // find from cloud
size_t max_x = … // find from cloud
size_t dx = (max_x - min_x) / num_rows;

size_t min_y = … // find from cloud
size_t max_y = … // find from cloud
size_t dy = (max_y - min_y) / num_cols;

vector<vector<Point>> rows(num_rows);

for (size_t i = 0, row = 0; i < cloud.size(); i++) {
	if (cloud.points[i].x > min_x + row * dx) {
		row++;
	}

	rows[row].push_back(cloud.points[i]);
}

vector<vector<vector<Point>>> table(rows.size());

for (size_t row = 0; row < rows.size(); row++) {
	table[row] = vector<vector<Point>>(num_cols);

	for (size_t j = 0, col = 0; j < rows[row].size(); j++) {
		if (rows[row][j].y > min_y + col * dy) {
			col++;
		}
		table[row][col].push_back(rows[row][j]);
	}
}