filte to pic

CModule::IncludeModule('iblock');
//PARAMS
$iblockId = 6;
$propArticul = 'CML2_ARTICLE';
$propPhoto = 'MORE_PHOTO';
$baseDir = $_SERVER['DOCUMENT_ROOT'] . '/upload';

//ACTION
$el = new CIblockElement;
$rs = CIblockElement::GetList([],['IBLOCK_ID' => $iblockId], false, false, ['ID', 'IBLOCK_ID', 'PROPERTY_' . $propArticul]);
while($ob = $rs->GetNext()){
    $fileMask = $ob['PROPERTY_'] . $propArticul . '_VALUE';
    if(!empty($fileMask)){
        if($mainPic = glob("{$baseDir}/{$fileMask}.*")) {
            //$mainPic
            //$el->Update($ob['ID'], ['']);
        }

        //MORE_PHOTO
        $arMorePhotoFilesIds = [];
        foreach(glob("{$baseDir}/{$fileMask}_*.*") as $docFile) {
            //write files
        }

        //CIblockElement::SetPropertyValueEx();
    }
}