The main difference is that annotations are meant to be notes, or sketches for reference only. There is no way to render them and cannot be animated.
Grease pencil objects are renderable, and can be animated. They are designed as a "hand drawn" animation tool in a 3D environment.
The Annotation layers can also be found in the View Panel in the Right hand side panels. (Toggle with N)
You don't need to be using the Annotate tool to access it.
To keep it in place, right click on the sub-panel header and choose Pin. You can also use SHIFT + Left Mouse. Notice the Pin icon in the top right.
Click and drag the 8 dots in the top right of ...
Selecting again the Annotate tool will display a menu in the header. By default an annotation layer called "Note" is used.
From that menu, the layer visibility can be toggled, as well as adding / removing layers, and changing some little things like the color and the thickness.
Note: if the header is hidden, it can be displayed again using the little ...
When you create an Annotation , it is used to be used as a reference , for example you can use to annotate a bad geometry in object mode and then go to wireframe mode fr solving that problem still knowing where it is because to annotated it .On the other side , you can use Grease pencil to make 2d animations in the Blender 2d preset and also to serve the ...
By default the depth is determined by the 3D cursor position.
All the settings are in the N panel > Tool > Active Tool > Placement, you can choose between:
3D Cursor: The annotation is drawn perpendicularly to your view and it is placed where your 3D cursor is.
View: The annotation does not depend on the 3D view.
Surface, The annotation is drawn on ...
When in edit mode press Right Click > Decimate curve, Then in the bottom left corner click on the foldout (Or press F9) and set the decimation ratio.
This will keep the original shape more precisely than deleting every other vertex.
The code given in the linked answer as you rightfully point out only works in Blender 2.80. I cannot find the source at the moment, but I read somewhere that __annotations__ have been added to Blender 2.80 for exactly the reason you are trying to use it: So that a user can conveniently check out custom added properties that came from Add-ons. There is no ...
For part a) You can selected every other vertex by the select checker deselect method. In edit mode select all verticies that you want to "unsubdivide", then through the Select menu, choose Checker Deselect (Note this has . Be cautious of selecting the end points of your curve.
However I am sure there may be better ways?
I found the answer. The top tab of the 3D view has Annotation tool information, and if you hit the "Note" drop-down, it has a field that says what frame the annotation was drawn on, and says either "locked" or "unlocked."
If you click on the field you can set it to "locked," and the drawing will now appear every frame....
To delete all the measurements select individual measurement and click x to delete each of them .While selecting don't click in the middle of those lines(It will only add an angle and if you click x it will only delete the angle) instead click on any end point.
It is a tedious job if you have many measurements.
You can pass the property reference to the dir() function in order to get the list of properties.
Proof using the Console:
>>> props = C.scene.my_addon_properties
>>> for attr in dir(props):
... if hasattr(props, attr):
... print( "props.%s = %s" % (attr, getattr(props, attr)))