CtrEditor/ObjetosSim/ucGuia.xaml

<UserControl x:Class="CtrEditor.ObjetosSim.ucGuia"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d"
             xmlns:convert="clr-namespace:CtrEditor.Convertidores">

    <UserControl.Resources>
        <convert:MeterToPixelConverter x:Key="MeterToPixelConverter"/>
    </UserControl.Resources>

    <Canvas>
        <Rectangle x:Name="Guia" Width="{Binding Ancho, Converter={StaticResource MeterToPixelConverter}}" Height="{Binding AltoGuia, Converter={StaticResource MeterToPixelConverter}}" Fill="Blue">
            <Rectangle.RenderTransform>
                <RotateTransform Angle="{Binding Angulo}"/>
            </Rectangle.RenderTransform>
        </Rectangle>
    </Canvas>

</UserControl>