How to find background image's path ? (2.93)

Question

I wrote a script based on Exiftool that reads RollAngle, PitchAngle, FocalLength, ImageWidth, ImageHeight and Timestamp #tags from a digital photography's EXIF data. It then matches Blender's camera X and Y rotation and focal length, X and Y res and Sun Position's date and time parameters with values read from the EXIF.

So when adding a mesh, it's 'automagically' aligned with the real-life picture/world. Using it as a camera background allows for (almost) seamless inserting of 3D objects in 'reality'. Check the odd thing on the stage, in the attached image.

I try to img = bpy.something.background_image.pathand getVal(img) because Blender doesn't load EXIF data, and of course my getVal() function relies on them. But so far, the API reference, tooltips and button context menu research didn't help. It works if I manually assign the path to a variable within the code, but it's a pain.

`import bpy
 import sys
 import os
 import math
 from exiftool import ExifToolHelper
 lv=[0]# liste valeurs
 def getVal(im) :
 with ExifToolHelper() as et:
    try :
        for d in et.get_tags(im,tags =   ["RollAngle","PitchAngle","FocalLengthIn35mmFormat","ImageWidth","ImageHeight","TimeStamp"]):
            for  v in d.values():
                lv.append(v)
    except :
        pass
return (lv) 

rad = math.radians
cam=bpy.data.objects['Camera']
cam.data.show_background_images=True
# using this block doesn't work and returns 'list index out of range'
items = bpy.data.cameras['Camera'].background_images.items()
camera_image = items[0][1]
filepath = camera_image.image.filepath
prms = getVal(filepath)# if I 'print(prms)' prints '[0]'

#this block works, provided my camera object is selected
#Img = "/home/user/Images/2019/20191030/P1040273.jpg"
#prms = getVal(Img)

cam.rotation_euler[0] = rad(prms[2])+rad(90)# zero RL camera roll = 90° rotation on X axis in Blender
cam.rotation_euler[1] = rad(prms[3])# y rotation
cam.rotation_euler[2] = 0 # my cameras don't have magnetic sensors
bpy.data.objects["Camera"].lock_rotation[0]# this doesn't work either
bpy.data.objects["Camera"].lock_rotation[1]
bpy.data.objects["Camera"].lock_location[2]
cam.location[0] = 0
cam.location[1] = 0
cam.location[2] = 1.7# my eyes' height
#print(prms)
bpy.data.cameras["Camera"].lens = prms[4]
bpy.data.scenes["Scene"].render.resolution_x=prms[5]
bpy.data.scenes["Scene"].render.resolution_y=prms[6]
stamp = prms[-1].split(' ')
date = stamp[0].split(':')
time = stamp[1].split(':')
hours = time[0]
mins = time[1]
secs = time[2]
#########sun pos date##########
bpy.context.scene.sun_pos_properties.year = int(date[0])
bpy.context.scene.sun_pos_properties.month = int(date[1])
bpy.context.scene.sun_pos_properties.day = int(date[2])
#########sun pos time##########
decimals = (int(mins)*60+int(secs))/3600
bpy.context.scene.sun_pos_properties.time = float(hours)+decimals
#bpy.context.scene.sun_pos_properties.latitude = 43.152
#bpy.context.scene.sun_pos_properties.longitude = -3.1

`

Answer 1

You need to find the bpy.data.images entry for the image. If you know the name of the image but not the path you can use bpy.data.images[NAME]

Once you know the entry, the full file path is in the filepath member, so something like bpy.data.images['foo.png'].filepath will return the full path to the image.

If you don't know the name, but you know you have only a single camera background image, you can use bpy.data.cameras['Camera'].background_images.items() to fetch a list of all of the background images associated with the camera. Here's what the list looks like when there is only one image:

[(0, bpy.data.cameras['Camera']...CameraBackgroundImage)]

You can find the bpy.data.Images entry from the second member of the tuple, so

items = bpy.data.cameras['Camera'].background_images.items()
camera_image = items[0][1]
filepath = camera_image.image.filepath

Will give you the full path to the first camera background image. For an non-camera background image you need to find the empty associated with the background image. Here's how to get the filepath for a background that's associated with an empty with the default name

filepath = bpy.data.objects['Empty'].data.filepath

UPDATE: about relative paths

If you have blender set up to use relative paths, filepath will be a path that starts '//' indicating that it is relative to the directory where your blend file is stored. To pass this as an absolute path to functions that require such things, instead of filepath, use bpy.path.abspath(filepath).