CtrEditor/ObjetosSim/UserControls/ucVMmotorSim.xaml

<UserControl x:Class="CtrEditor.ObjetosSim.ucVMmotorSim"
             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" 
             xmlns:local="clr-namespace:CtrEditor.ObjetosSim"
             mc:Ignorable="d"
             xmlns:convert="clr-namespace:CtrEditor.Convertidores">

    <UserControl.Resources>
        <convert:MeterToPixelConverter x:Key="MeterToPixelConverter"/>
    </UserControl.Resources>
    
    <Grid>
        <Image Source="{Binding ImageSource}"
           Width="{Binding Tamano, Converter={StaticResource MeterToPixelConverter}}"
           Height="{Binding Tamano, Converter={StaticResource MeterToPixelConverter}}"
           Stretch="Uniform"/>
    </Grid>

</UserControl>