More and more I have to deliver different versions from the project. One for television one for web, social media, and so on. Many times the aspect ratio and the resolution varies quite much. That’s why I created this simple but useful asset to help me to see how one render looks in different aspect ratios.

Note that the aspect ratio guide should be placed under the camera object.

Some calculations in Pythonish pseudocode:

doc = c4d.documents.GetActiveDocument()
temp_height = distance_from_camera * math.tan((camera_fov_ver * 0.5)) * 2.0
temp_width = distance_from_camera * math.tan((camera_fov_hor * 0.5)) * 2.0

guide_position_x = temp_width * film_offset_x
guide_position_y = temp_height * film_offset_y * -1

old_aspect_ratio = resolution_width / resolution_height # Calculate aspect ratio
if old_aspect_ratio > new_aspect_ratio: # If old aspect ratio is bigger than new aspect ratio
    guide_width = temp_height * new_aspect_ratio
    guide_height = temp_height
elif old_aspect_ratio < new_aspect_ratio: # If old aspect ratio is smaller than new aspect ratio
    guide_width  = temp_width
    guide_height  = temp_height / new_ar
else: # If old and new aspect ratios are same
    guide_width  = temp_height
    guide_height  = temp_width

Supports:

• Perspective Projection
• Focal Length changes
• Sensor Size changes
• Film offset changes
• Render resolution changes
• Position Z changes

Updated 31/08/2023
> Resolution result bug fix

Included in AR_Scripts!

ar_aspect_ratio_guide.c4d v1.1.1 (2023.1.2)