<?php if(isset($node->field_image_undernav) && count($node->field_image_undernav) > 0):?>
    <?php $imagePath = file_create_url($node->field_image_undernav['und'][0]['uri']); ?>
    <img class="img-responsive" id="img-top" src="<?php print $imagePath;?>"/>
<?php endif; ?>

{# Top Image #}
    {% if machine_name_of_field %}
       {% block machine_name_of_field %}
         {{ machine_name_of_field }}
    {% endblock %}
{% endif %}