nvm的格式如下:
NVM_V3 [optional calibration] # file version header
<Model1> <Model2> ... # multiple reconstructed models
<Empty Model containing the unregistered Images> # number of camera > 0, but number of points = 0
<0> # 0 camera to indicate the end of model section
<Some comments describing the PLY section>
<Number of PLY files> <List of indices of models that have associated PLY>
The [optional calibration] exists only if you use "Set Fixed Calibration" Function
FixedK fx cx fy cy
Each reconstructed <model> contains the following
<Number of cameras> <List of cameras>
<Number of 3D points> <List of points>
The cameras and 3D points are saved in the following format
<Camera> = <File name> <focal length> <quaternion WXYZ> <camera center> <radial distortion> 0
<Point> = <XYZ> <RGB> <number of measurements> <List of Measurements>
<Measurement> = <Image index> <Feature Index> <xy>
Documentation原文说”As for the image coordinate system, X-axis points right, and Y-axis points downward, so Z-axis points forward.”
即X轴指右,Y轴指下,Z轴指前。这和openGL与Unity的坐标系统都不同,使用时注意坐标矫正。