5_optimize_projector_pose.py

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# This script optimizes projector's position and direction using differentiable rendering.

import os
import time

import enoki as ek
import mitsuba
mitsuba.set_variant('gpu_autodiff_rgb')

from mitsuba.core import Float, Thread
from mitsuba.core.xml import load_file
from mitsuba.python.util import traverse
from mitsuba.python.autodiff import render, write_bitmap, Adam
import time
import os

import pyexr
import numpy as np

import matplotlib.pyplot as plt
import pyexr
import numpy as np

from mitsuba.core import xml, Thread, Transform4f, ScalarPoint3f, Bitmap, Float, Vector3f, UInt32, Point3f
from mitsuba.python.util import traverse
from mitsuba.python.autodiff import render, render_torch, write_bitmap, Adam, SGD


from common import *


def projector_pose_template(pos, rot):
    return \
        "<?xml version='1.0' encoding='utf-8'?>\n"+\
        "<scene version=\"0.5.0\">\n"+\
        "    <point name=\"position\" value=\""+str(pos)[2:-2]+"\"/>\n"+\
		"    <vector name=\"rotation\" value=\""+str(rot)[2:-2]+"\"/>\n"+\
        "</scene>\n"


if __name__ == "__main__":

    os.chdir(scene_path)

    # Prepare output folder
    output_path = 'pose_output/'
    if not os.path.isdir('pose_output'):
        os.makedirs('pose_output')

    # Load example scene
    scene_folder = './'
    Thread.thread().file_resolver().append(scene_folder)
    scene = xml.load_file('out_scene_for_pose.xml', integrator="flag")

    ref = read_exr('color_proj_dist.exr')

    params = traverse(scene)

    # Discard all parameters except for one we want to differentiate
    params.keep(["Projector.position", "Projector.rotation"])

    params.update()

    iter_lr = [(1000, 1),
               (2500, 0.08)]

    it = 0

    time_a = time.time()

    for (start_iter, lr) in iter_lr:

        opt = Adam(params, lr=lr)

        while True:

            # Perform a differentiable rendering of the scene
            with Float.Scope("rendering..."):
                image = render(scene, optimizer=opt, spp=1, unbiased=True)
            
            if it%20 == 0:
                write_bitmap(output_path + 'out_%07i.png' % it, image, (640, 480))
            
            with Float.Scope("computing loss..."):
                ob_val = ek.hsum(ek.sqr(image - ref)) / len(image)


            ek.backward(ob_val)

            # Optimizer: take a gradient step -> update displacement map
            opt.step()

            if it%20 == 0:
                print('[Enoki] Iteration %03i: error=%g' % (it, ob_val[0]), params["Projector.position"], params["Projector.rotation"])
            it += 1
                        
            if it == start_iter:
                break
                
    time_b = time.time()
    print('total : %f' % (((time_b - time_a) * 1000000)), 's')

    f = open("projector_pose.xml", 'w')
    f.write(projector_pose_template(params["Projector.position"], params["Projector.rotation"]))
    f.close()