python实现obj模型的归一化
作者：石炜贤&曾翔钰
归一化，个人理解就是将数据范围映射到另一个更小的范围。比如，我们即将要说到的obj模型的归一化，原始的数据坐标范围是-100多到+100多，这里我要将它归一化到-1~1的范围。
具体步骤如下：
- 读取每个点的信息，计算这个模型的包围盒（好吧，其实就是找到这个模型最小的x,y,z和最大的x,y,z。注意，这里不是最小的点和最大的点的坐标。）
def get_bounding_box(self, p):
"""
获取物体的最小x,y,z和最大的x,y,z
:param p:
:return:
"""
self.minP.x = p.x if p.x < self.minP.x else self.minP.x
self.minP.y = p.y if p.y < self.minP.y else self.minP.y
self.minP.z = p.z if p.z < self.minP.z else self.minP.z
self.maxP.x = p.x if p.x > self.maxP.x else self.maxP.x
self.maxP.y = p.y if p.y > self.maxP.y else self.maxP.y
self.maxP.z = p.z if p.z > self.maxP.z else self.maxP.z- 通过第一步的x,y,z我们得到（max_x-min_x），（max_y-min_y）和(max_z-min_z)三者中的最大值，取最大值作为包围盒的边长，构建一个正方体式的包围盒。现在，想象这个 obj模型被包围盒包着并处于包围盒的中心。
def get_bounding_box_length(self):
"""
获取包围盒的最大长度
:return:
"""
box_len = self.maxP.x - self.minP.x
if box_len < (self.maxP.y - self.minP.y):
box_len = self.maxP.y - self.minP.y
if box_len < (self.maxP.z - self.minP.z):
box_len = self.maxP.z - self.minP.z
return box_len- OK，我们剩下要做的就是简单的将坐标放缩一下而已了。
def do_normalize(self, box_len, points):
"""
归一化处理
:param center_p: 物体的中心点
:param box_len: 包围盒的一半
:param points:要进行归一化处理的点
:return:
"""
new_points = []
for point in points:
x = (point.x - self.minP.x) * 2 / box_len - 1
y = (point.y - self.minP.y) * 2 / box_len - 1
z = (point.z - self.minP.z) * 2 / box_len - 1
new_points.append(Point(x, y, z))
return new_points
完整代码如下：
运行的话，只需写入存放obj文件的文件夹路径（或者父路径也行）。
# encoding:utf-8
import os
class Point(object):
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
class MyFile(object):
folders = []
outFolders = []
count = 0
def get_folder_paths(self, base_path):
"""
获取文件夹下所有含有obj文件的文件夹路径
:param base_path:
:return:
"""
self.folders.append(base_path)
files = os.listdir(base_path)
contain_obj = False
for file in files:
file_path = os.path.join(base_path, file)
if os.path.isdir(file_path):
self.get_folder_paths(file_path)
print(file_path)
self.folders.append(file_path)
elif os.path.isfile(base_path + file):
contain_obj = True
if contain_obj is not True:
self.folders.remove(base_path)
def get_obj_filenames(self, folder_path):
filenames = []
files = os.listdir(folder_path)
for file in files:
file_path = os.path.join(folder_path, file)
if os.path.isfile(file_path) and file[-3:] == "obj":
print("file:", file)
filenames.append(file)
self.count += 1
return filenames
def get_out_folders(self):
for folder in self.folders:
new_folder = str(folder).replace("Budata\\BU_3DFE", "NEW_NormalizeDataWithoutRound")
self.outFolders.append(new_folder)
# print(new_folder)
if not os.path.exists(new_folder):
os.makedirs(new_folder)
class MyNormalize(object):
minP = Point(1000, 10000, 10000)
maxP = Point(0, 0, 0)
def get_bounding_box(self, p):
"""
获取物体的最小x,y,z和最大的x,y,z
:param p:
:return:
"""
self.minP.x = p.x if p.x < self.minP.x else self.minP.x
self.minP.y = p.y if p.y < self.minP.y else self.minP.y
self.minP.z = p.z if p.z < self.minP.z else self.minP.z
self.maxP.x = p.x if p.x > self.maxP.x else self.maxP.x
self.maxP.y = p.y if p.y > self.maxP.y else self.maxP.y
self.maxP.z = p.z if p.z > self.maxP.z else self.maxP.z
def get_bounding_box_length(self):
"""
获取包围盒的最大长度
:return:
"""
box_len = self.maxP.x - self.minP.x
if box_len < (self.maxP.y - self.minP.y):
box_len = self.maxP.y - self.minP.y
if box_len < (self.maxP.z - self.minP.z):
box_len = self.maxP.z - self.minP.z
return box_len
def do_normalize(self, box_len, points):
"""
归一化处理
:param center_p: 物体的中心点
:param box_len: 包围盒的一半
:param points:要进行归一化处理的点
:return:
"""
new_points = []
for point in points:
x = (point.x - self.minP.x) * 2 / box_len - 1
y = (point.y - self.minP.y) * 2 / box_len - 1
z = (point.z - self.minP.z) * 2 / box_len - 1
new_points.append(Point(x, y, z))
return new_points
def read_points(self, filename):
"""
读取一个obj文件里的点
:param filename:
:return:
"""
with open(filename) as file:
points = []
while 1:
line = file.readline()
if not line:
break
strs = line.split(" ")
if strs[0] == "v":
points.append(Point(float(strs[1]), float(strs[2]), float(strs[3])))
if strs[0] == "vt":
break
return points
def write_points(self, points, src_filename, des_filename):
"""
将归一化好的点保存到另一个文件
:param points:
:param src_filename:
:param des_filename:
:return:
"""
point_lines = []
for point in points:
point_line = "v " + str(point.x) + " " + str(point.y) + " " + str(point.z) + "\n"
point_lines.append(point_line)
with open(src_filename, "r") as file:
outFile = open(des_filename, "a")
for point in points:
point_line = "v " + str(point.x) + " " + str(point.y) + " " + str(point.z) + "\n"
outFile.write(point_line)
outFile.flush()
while 1:
line = file.readline()
if not line:
break
strs = line.split(" ")
if strs[0] == "f":
outFile.write(line)
outFile.flush()
outFile.close()
if __name__ == "__main__":
myFile = MyFile()
myNormalize = MyNormalize()
basePath = "H:\\Budata\\BU_3DFE\\"
myFile.get_folder_paths(basePath)
myFile.get_out_folders()
count = 0
for folder in myFile.folders:
outFolderPath = myFile.outFolders.pop(0)
print(outFolderPath)
objFilenames = myFile.get_obj_filenames(folder)
for objFilename in objFilenames:
# 读取obj文件的坐标点
objFilePath = os.path.join(folder, objFilename)
points = myNormalize.read_points(objFilePath)
for point in points:
myNormalize.get_bounding_box(point)
# 包围盒长度
boxLength = myNormalize.get_bounding_box_length()
# 归一化
points = myNormalize.do_normalize(boxLength, points)
# 将归一化的坐标点写入目标文件
myNormalize.write_points(points, os.path.join(folder, objFilePath),
os.path.join(outFolderPath, objFilename))
count += 1
print("第", count, "个执行完毕")
print("执行结束")