Parsing large XML file

I need to (basically) rewrite a large xml file. It's too large to use simplexml_load_file so instead have been trying to use XMLReader and then use a foreach statement to access keys and values.
This works fine for accessing most nodes but there are some that are not so straight forward.
Example:
<number1 name="Land area (+/- 5%) in m2 " value="4500"/>
<number2 name="Habitable area (+/- 5%) in m2" value="200"/>
<number3 name="DPE numeric value (Admin) " value="274"/>
where I need to access the name and value values.

There are also nodes with children that I need to access
Example:
<pictures>
     <picture name="Photo 6">
          <filename>http://etc.jpg </filename>
     </picture>
     <picture name="Photo 7">
          <filename>http://etc.jpg</filename>
     </picture>

Searching forum and googling has left me confused.

I need to extract the fields we require and rewrite into another (simpler) xml file.
Any help with this will me most appreciated.