Animated Render Border

by Ray Mairlot's Shop in Scripts and Addons

Animated Render Border User Guide

This documentation is also available as a PDF when you download the product.


The Animated Render Border script is a single python text file and can be installed in the same way as other add-ons. You can install it by going to File > User Preferences > Add-ons > Install from File. Browse to and select the ‘’ file and press ‘Install from file’. The add-on should then automatically appear, which you can then enable by clicking the checkbox next to it. Once enabled, the ‘Animated Render Border’ panel will appear at the bottom of the ‘Render’ tab of the ‘Properties’ area, where all the other render settings are.



There are 3 different modes to animate the render border with: tracking an object, tracking a group of objects, or by animating the border values manually. These tracking types are referred to as ‘Object tracking’, ‘Group tracking’ and ‘Keyframe mode’.

The types of object that can be tracked are: Meshes, Text (Font objects), Curves, Surfaces, Meta objects, Lattices and Armatures.


Steps to start using ‘Object’ or ‘Group’ tracking

1. Enable tracking by clicking the checkbox next to the panel title.

2. If you are tracking a single object you can leave the tracking type on its default, otherwise change to ‘Group’ tracking.

3. Choose the object (or group) you wish to track by selecting it from the dropdown box. If this box is blank it means there are no trackable objects (or groups) in the scene.

4. Press '0' (zero) to look through the active camera.

You can now scroll in the timeline and, whether your object is animated or still, the render border will move to match the object’s position. You may wish to refine the tracking using the ‘Margin’ and ‘Use Bounding Box’ options (explained in the ‘Options’ section).   If you wish, your object can now be rendered (using the ‘Animated Render Border’ custom ‘Render Animation’ button) and the render border will update accordingly for each rendered frame.

If you want to turn off tracking either temporarily or permanently you can click the checkbox next to the panel name.  

Steps to start using ‘Keyframe’ mode

1. Enable tracking by clicking the checkbox next to the panel title.

2. Change to ‘Keyframe’ tracking mode.

3. Press '0' (zero) to look through the active camera.

4. Move to the frame in the timeline that you want to place the first keyframe for the render border on.

5. Either manipulate the ‘Min X’, ‘Max X’, ‘Min Y’ or ‘Max Y’ UI values or draw the border in the viewport using the regular Ctrl+B shortcut to define the size and position of the border.

If you manually draw the border in the viewport the min/max values in the panel will not immediately update, instead, a ‘Refresh to synchronise border values’ button will appear, which, when pressed will update the values. Refreshing is only necessary if you wish to tweak the border values after manually drawing a border, otherwise you can insert a keyframe, shown in the next step, as normal.

6. Once you are happy with the size and position of the render border press the ‘Insert Keyframe’ button to insert a keyframe for all 4 border values. You can alternatively, right-click on an individual border value and choose ‘Insert Keyframe’ or simply press ‘I’ while the cursor is over the value to insert a keyframe for just that value.

7. Repeat steps 4, 5 and 6 to insert keyframes for a different sized border on a different frame.

You can now scroll in the timeline and the border will move depending on the keyframes you have set. To remove a keyframe you can either do so via the ‘Dope Sheet’ editor, or by right-clicking on the keyframed value and choosing ‘Delete Keyframe’ or alternatively, you can use the ‘Delete Keyframe’ button in the panel, which will delete keyframes for all 4 values at once.

If you wish, your object can now be rendered (using the ‘Animated Render Border’ custom ‘Render Animation’ button) and the render border will update accordingly for each rendered frame.  

If you want to turn off tracking either temporarily or permanently you can click the checkbox next to the panel name.  


Options for all 3 tracking modes

Enable/Disable (default ‘False’)

Python: scene.animated_render_border.enable (Type: Bool)

This is the checkbox that appears next to the panel name and allows you to easily turn on or   off the tracking without having to remove the tracking object or group (which, if blank,   would also disable tracking) or keyframes. When turning this on it will turn on the  render  border option in the Render> Dimensions panel if it isn’t already  on. It won’t,  however, turn off the render border when disabling it.

Type (Object, Group or Keyframe, default ‘Object’)

Python: scene.animated_render_border.type (Type: Enum in [‘Object’, ‘Group’, ‘Keyframe’])

The type of tracking to perform: either track a single object, a group of objects or manually   keyframe the border values. The exact object or group to track is specified later  on.

Render Animation 

Python: bpy.ops.render.animated_render_border_render()

The default ‘Render Animation’ button in Blender does not allow the render border to   update each frame, so a custom ‘Render Animation’ button is needed. Once pressed,   the mouse cursor will turn into a percentage counter and will update as the  render  progresses.

This does not affect still frames, which can be rendered using the normal ‘Render’   button.

The render can be cancelled by pressing the ‘Esc’ key on the keyboard. This doesn’t   immediately cancel the render though, as the current frame has to finish  rendering  before it will stop.

The ‘Render Animation’ button will appear disabled and display a ‘Fix errors to render’   message if there are any issues which would stop the render from operating  correctly.  These various issues are covered in the ‘Warnings’ section later  on. The button  will also be disabled if nothing is selected to be tracked  when in ‘Object’ or  ‘Group’ tracking mode.


Options for ‘Object’ and ‘Group’ tracking

Object or group to track (cannot be blank when tracking type is   ‘Object’ or ‘Group’)

Python: scene.animated_render_border.object (Type: String)
Python: (Type: String)

When ‘Object’ or ‘Group’ tracking has been selected you can select your chosen object   (or group) from the dropdown box. If this dropdown box is blank it means  there  are either no trackable objects in the scene or no groups.

The types of object that can be tracked are: Meshes, Text objects, Curves, Surfaces,   Meta objects, Lattices and Armatures. If you have selected ‘Group’  tracking  and the group contains object types that are not in this list  then they will  not be taken into account when doing the tracking.

Bone (optional, only appears for ‘Object’ tracking when  the  chosen object is an armature)

Python: scene.animated_render_border.bone (Type: String)

If you have selected ‘Object’ tracking mode and have chosen to track an armature,   this optional property appears. This drop-down box allows you to  select a  specific bone to track; if this is left blank all the  bones in the armature  will be tracked.

Margin (default ‘3’)

Python: scene.animated_render_border.margin (Type: Int)

This allows you to increase or decrease the border around the tracked  object(s).

Use Bounding Box (default ‘True’)

Python: scene.animated_render_border.use_bounding_box (Type: Bool)

By default, the tracking will calculate where the render border has  to  be by looking at the bounding box of the object. This  is relatively  quick as there are only 8 points of the bounding  box (the corners)  to analyse, but can appear slightly inaccurate  depending on the orientation  of the object.

Turning this option off switches to a slower, more precise method,   which analyses the ‘inner points’ of the object i.e.  vertices  if it’s a mesh, the lattice points for lattices,  bones for armatures  and so on, depending on the object  type. Out of the types of  objects that can be tracked,  the following object types do not  have any ‘inner points’  and so can’t use this precise method:  Text objects  and Meta objects. When one of these objects is tracked,  the  ‘Bounding Box’ option will be turned on and cannot be turned   off. If you are using ‘Group’ tracking and have ‘Bounding  Box’  turned off, then ‘inner points’ will be used on  any objects in  the group that support that; ones that  don’t will fall back to  the bounding box method.

While this ‘inner points’ method is more precise, it is slower  than  the bounding box method as it has to compare every  ‘inner point’  of the object, but results in a very  precise calculation, creating  a very tight, accurate  border around the object. However, this  could get very  slow for objects with many inner points (e.g.  high  resolution meshes) or a group of many objects.

The exception to the precision ‘inner points’ offers is with  ‘Surface’  type objects as often their ‘inner points’  are far larger in  area than the displayed surface.  In this case, ‘Use Bounding  Box’ will probably  be preferable.

‘Inner points’ will also be the preferable option if your  object(s)  has geometry generated by a modifier  as the bounding box will  stretch to contain all  of the object whereas the ‘inner points’  will remain  in their pre-modifier positions.

Draw Bounding Box (default ‘False’)

Python: scene.animated_render_border.draw_bounding_box (Type: Bool)

Enabling this option will turn on the bounding box option  which is  a feature of Blender found on the ‘Object’  tab of the selected  object. This displays the box  that Blender has calculated as  the ‘bounds’ of  the object and can be helpful when deciding whether  ‘bounding  box’ tracking or ‘precision’ tracking will be more  suitable  for your object(s).


Options for ‘Keyframe’ tracking

Insert Keyframe

Python: bpy.ops.render.animated_render_border_insert_keyframe()

                This   button inserts a keyframe for all 4 bounding  box values on  the current frame.

Delete Keyframe

Python: bpy.ops.render.animated_render_border_insert_keyframe()

                This   button deletes a keyframe for all 4 bounding  box values on  the current frame.

Min X (default ‘0’), Max X (default ‘1’), Min Y (default ‘0’), Max Y (default ‘1’)

Python: scene.animated_render_border.border_min_x, …border_max_x, …border.min_y, …border.max_y (Type: Float)

These are the values that represent the left, right,  bottom and  top edges of the render border box.  Because a render border  cannot have ‘0’ width  or ‘0’ height, the minimum and maximum  values  on a single axis (x or y) cannot be the same. To  adjust  for this, if the min value is set to  the same as the max  value for either the x  or y axis, 0.01 will be added to the  max value.  In the same manner, if the max value is set to  the  same as the min value, 0.01 will be subtracted from  the  min value.

The minimum values also cannot be more than the maximum  values,  nor the maximums less than the  minimums. If a value tries  to go beyond  these limits the other value will adjust  to  compensate. For example, increasing the minimum  value  up to and beyond the maximum value  will cause the maximum  value to increase  so it is always at least 0.01 units  more  than the minimum.

Refresh to synchronise border values

Python: bpy.ops.render.animated_render_border_refresh_values()

This button appears when the UI values representing  the minimum  and maximum of the render border  have got out of sync  with the actual values.  This happens when the render  border is  drawn manually in the viewport. Pressing the   button will update all the UI values to  the values of  the actual render border.  This is useful if you wish  to tweak the  render border values after manually drawing  it.  If you don’t need to tweak the values and just  wish  to insert a keyframe then you don’t  need to refresh them.


There are various warnings that will appear so  as to  alert you to things that will  stop the render from  rendering correctly.  These need to be fixed before  a render  can be started, or in the case of rendering   using Python, will cause an error to  be thrown.

‘Border’ is disabled in ‘Dimensions’ panel

If the Animated Render Border panel is enabled  but the  ‘border’ option has been turned  off, either with  a shortcut or via  the Render> Dimensions panel,  this warning will appear. This warning is   accompanied by a ‘Fix’ button, which,  when pressed  will turn the border option  back on.

Active camera must be a Camera object, not [object type]

Via the ‘Set Active Object as Camera’ Blender  command  it is possible to set an  object which is not  a camera as  the active scene camera. Obviously,  a  render cannot be started if the scene  camera  is anything other than a  camera type object.  Change the  camera object in the ‘Scene’ properties   to a camera object to remove this  error.

No camera is set in the scene properties

This error deals with a situation where  this  is no camera set to be  rendered from. Similar  to the  previous error, this can be fixed   by going to the ‘Scene’ properties  and selecting  a camera from  the drop-down list. If no cameras   are in this list, then one  must be added  to the scene.

The object selected to be tracked does not exist

If an object is selected to be tracked,  but  that object is subsequently  renamed,  the add-on will  no longer be able to  detect  or track that object. To correct   this error re-select the  object to be  tracked from  the object drop down list.  This  error will also appear when the   selected object has been  deleted.

The group selected to be tracked does not exist

If a group is selected to be  tracked,  but that group  is subsequently renamed,   the add-on will no  longer be able  to detect  or track that group. To  correct  this error re-select the   group to be tracked  from the group  drop  down list. This error will  also  appear when the  selected group has  been  deleted.

The selected group has no trackable objects

If the group to be tracked  is empty  or none  of the objects can be   tracked, this error  appears.  The group  must contain one of  the  following types of object   for tracking to  be possible:  Meshes,  Text objects, Curves,   Surfaces, Meta  objects, Lattices,  Lamps  or Armatures.

“Armatures objects can only use bounding box tracking in Blender 2.76 and later.”

“Lattice objects can only use bounding box tracking in Blender 2.76 and later.”

“Armature or Lattice objects in this group can only use bounding box tracking in Blender 2.76 and later.”

These 3 separate error  messages  are  related to users  using  a version  of Blender prior   to version  2.76. Blender  2.76  has a specific change   in its code  which allows  access  to the bounding boxes   of Armature  and Lattice objects.   Previous versions  of Blender  do  not have this and  so the  add-on  will automatically   turn off and  disable the  ‘Use  Bounding Box’ option   when an Armature,  Lattice,  or  group containing  either  of those  object types is  selected  when the add-on  detects  Blender 2.75 or earlier   is being used.  This doesn’t  stop  the object being  tracked,  it  just means you can’t  use  the bounding  box to track  it.  Instead, it will  resort  to the  ‘inner points’ method   described in  the “Options  for  ‘Object’ and ‘Group’   tracking” >  “Use Bounding  Box”  section of this user   guide document.

These are the only  warnings  which  will not stop  the  user  from being able   to render.  If you are  using  Blender 2.76  or  later  you will not  see  these  warnings as Armatures   and Lattices  can be tracked   like any  of the other   trackable  objects.


User Preferences

The add-on’s  user preferences   appear  below the  panel  in  Blender’s  user preferences   where  you enable  the  add-on.  Once the  add-on  is  enabled the  add-on’s   user  preferences  box  will  appear below  it.

Display border dimensions (default ‘False’)

Python: bpy.context.user_preferences.addons['animatedRenderborder'].preferences.display_border_dimensions (Type: Bool)

This user preference,  which  is  off by default,  turns  on  a label whose  only  function  is to display   in  pixels the  size of  the  bounding  box. The   label  appears below  the  ‘Render  Animation’  button  for  all 3 tracking  types  when  turned on.


Is Command Line rendering supported?

Yes. However  the command   to  get it  to work   is  slightly  different   from  the normal  command   line  command.

In a normal  command  line   render  you would   use  ‘-a’  at the  end  of  the command  to  indicate  to blender that  you are rendering   an  animation,  but  this  would  use the   default  render  command,   not  the Animated   Render  Border  Render  command.

To fix this,  instead   of  using  ‘-a’  we  use  ‘—python-expr’   (Python  Expression)   which  allows  us to   specify  a specific   python  command  to  run.  In this  case,   specifying  that  we  want  to run  the ‘bpy.ops.render.animated_render_border_render()’   command is not  enough   to  get the  render   to  work  and will   result  in an  error,   probably  saying  that   ‘bpy’  is not  defined.   This  is exactly  the  same  as if  we were   running  a Python   command  in blender;   only  after  importing   ‘bpy’  will  ‘bpy’   commands  be available.   So  the python  expression   we  need  to add  to  the  end of  the command   is:

--python-expr "import bpy; bpy.ops.render.animated_render_border_render()"

The semicolon  between   the  two commands   tells  blender  they   are  separate  and  the  quotes  around   the  entire  command   allows  for the  space   between  ‘import’   and  ‘bpy’.  For more   complex  commands   you  could  just  reference   a  python  file  using  one  of the  alternative   python  arguments.

The full  command  (minus   my  paths)  is:

blender-b "path to blend" --python-expr "import bpy; bpy.ops.render.animated_render_border_render()"

If you need  to add  extra   arguments  to the   command,  such  as  setting  the format   or  the output  path   these  arguments  should  go before the ‘—python-expr’   command,  otherwise   the  render  will  happen   before  they  are set   (because  the command   line arguments  are  executed  in the  order   they  are written).

How can I track objects that aren’t currently supported?

Ideally,  all objects   would  be trackable,   but  this  currently   isn’t  possible.  This   means  that  you can’t   currently  track  camera   objects,  empties   and  a few  other  object   types  and they  won’t   appear  in the  object   drop  down  list  and  will  be ignored  if  they  are present   in  the chosen  tracking   group.   

In the future,  hopefully   all  objects  will   be  supported  for  tracking,  but for   now  there  is a  useable   workaround.  If you   wanted to track  an  empty  you would  simply   have  to make  a cube   and  scale  it so  that   the  empty  is contained   within  the cube.   You can then  parent   the  cube  to the  empty   and  track  the cube   object  instead.  The  cube  doesn’t  have   to  be visible,  visible   in the render  or  even  on the  same   layer,  so it  should   be  relatively  unobtrusive.    


Is there a demo/tutorial video for this add-on I can watch?

Yes, there  is a  demo   video  on the  product   page  on the  Blender   Market  which  explains   both  why you  might   need  the add-on  and  how  to use  it, with   a  demonstration  of  all  the various  options.   Here  is the  direct   link  to that  YouTube   video:  

An updated  video  detailing   the  features  added   in  v2.0  of the  add-on   is  here:


What if I have problems/questions/suggestions and want to contact you?

If you need to contact me about this add-on with a problem, question or suggestion you can either contact me on the product page on the Blender Market or contact me at  [email  protected] .