How to determine model alignment points

[oly2b]

I trying to create a new wind-turbine and now have a ac model and the xml file but struggling to get the blades to spin central to the axis of the generator body, found a video on the wiki how to use Blender to finds the x, y, z values but the resolution of the video is low and not clear what parts of blender are being used and it was done using Blender 2.5 and Blender is now version 3.0

FlightGear Animations How to- Axis and Origins the easy way

I new to both Blender and AC3D

[Maerchenprinz]

Hi oly2b!

I only know from memory how that works in AC3D (demo version is enough for this purpose):
Select ONE vertex which lies on the axis and enter the x,y,z values which AC3D displays at the top right (beware: the y and z values are swapped between AC3D and FG as well as the sign (+/-) of AC3D's z) into the <center> part of your xml.
One value (x,y or z) is irrelevant because the vertex lies on the axis no matter what value it is; enter this one as 1 or -1 (direction of rotation) into the <axis> part and the others as 0.

You can also determine TWO points by the method mentioned above and enter them into your xml like this (without the <center> part):

Code: Select all

<axis>   
   <x1-m> 4.9</x1-m>
   <y1-m> 7.1</y1-m>
   <z1-m>-1.0</z1-m>
   <x2-m> 5.9</x2-m>
   <y2-m>11.2</y2-m>
   <z2-m>-0.5</z2-m>
  </axis>

From https://wiki.flightgear.org/Howto:Animate_models

You can also just wait until someone who knows how to find the values in Blender answers your question here!

Ciao,

Adrian

[oly2b]

Many thanks for replying, I will give it go as I have a full copy of AC3D, I let you know how I get on.

[oly2b]

Silly question - used AC3D to determine the x1, y1, z1 and x2, y2, z2 points for the both ends of axis through my wind turbine (i.e axis of nose cone and generator body that the three blades rotate (spin around) but it results in a weird spin in fg
Where would you measure from?,
I though I allowed for the changes in between AC3d and FG coordinates.

[wlbragg]

From memory, in Blender, I usually select point of the object I want to measure position from while in edit mode, be it the center point or any point. Then use mesh, snap, cursor to selected. Make sure the "Transform toolbar is open "n" while in 3d window. Then you can read the position from 3d Cursor location. Make sure Blender is configured for the units you want. I think I leave mine in default which really line up with metric.

[TheEagle]

[Blender]

A wind turbine has a cone in the center of rotation. If the rotor isn't tilted, then it's very easy - simply select the cone, and in the sidebar on the right in the Item tab read off the X, Y and Z values - these go into the respective <center> tags in the animation file. As <axis> you'd simply set the axis your cone is parallel to (normally X) - for X, set <x>1</x> and Y and Z to 0: <y>0</y> <z>0</z>.

If your rotor is tilted, things are a little bit more complicated. In that case, first snap the cursor to the tip of the center cone and write down the X, Y and Z values (to be found in the right sidebar in the tab View, section Cursor), then select the vertices of the other end of the center cone, again snap the cursor to that and write down the coordinates (in Edit mode, use the menu item Mesh -> Snap -> Cursor to selected for snapping). Now in the animation file, instead of <axis> and <center> you use <x1-m>, <x2-m>, <y1-m>, etc … with the measured values. If you end up with the rotor turning the wrong way around, add a <factor>-1</factor> below the <property> tag (or reverse the sign of an existing <factor>).

If you have any problems on the way, just let me know !