estrutura-categorias.php

<?php 

//Código

            $terms = get_categories(array(
                        'type' => 'represent_map',
                        'taxonomy' => 'represent_map_type')
                    );
                    
            $categories = array();
            if (!empty($terms)) {
                foreach ($terms as $t) {
                    if (0 == $t->parent) {
                        $categories[$t->term_id] = $t;
                        unset($terms[$t->term_id]);
                    }
                }
            }
            
            foreach($terms as $cat) {
                if ( !empty($cat->name) && !empty($cat->parent) ) {
                    $categories[$cat->parent]->children[] = $cat;
                }
            }
    
            print_r($categories);



//Saída

/*
Array
(
    [18] => stdClass Object
        (
            [term_id] => 18
            [name] => Multiplataforma
            [slug] => multiplataforma
            [term_group] => 0
            [term_taxonomy_id] => 18
            [taxonomy] => represent_map_type
            [description] => 
            [parent] => 0
            [count] => 1
            [cat_ID] => 18
            [category_count] => 1
            [category_description] => 
            [cat_name] => Multiplataforma
            [category_nicename] => multiplataforma
            [category_parent] => 0
        )

    [9] => stdClass Object
        (
            [term_id] => 9
            [name] => Outdoor Tradicional
            [slug] => outdoor-tradicional
            [term_group] => 0
            [term_taxonomy_id] => 9
            [taxonomy] => represent_map_type
            [description] => 
            [parent] => 0
            [count] => 1
            [cat_ID] => 9
            [category_count] => 1
            [category_description] => 
            [cat_name] => Outdoor Tradicional
            [category_nicename] => outdoor-tradicional
            [category_parent] => 0
            [children] => Array
                (
                    [0] => stdClass Object
                        (
                            [term_id] => 5
                            [name] => Cartaz 9x3
                            [slug] => cartaz-9x3
                            [term_group] => 0
                            [term_taxonomy_id] => 5
                            [taxonomy] => represent_map_type
                            [description] => 
                            [parent] => 9
                            [count] => 1
                            [cat_ID] => 5
                            [category_count] => 1
                            [category_description] => 
                            [cat_name] => Cartaz 9x3
                            [category_nicename] => cartaz-9x3
                            [category_parent] => 9
                        )

                    [1] => stdClass Object
                        (
                            [term_id] => 7
                            [name] => Lonado 9x3
                            [slug] => lonado-9x3
                            [term_group] => 0
                            [term_taxonomy_id] => 7
                            [taxonomy] => represent_map_type
                            [description] => 
                            [parent] => 9
                            [count] => 1
                            [cat_ID] => 7
                            [category_count] => 1
                            [category_description] => 
                            [cat_name] => Lonado 9x3
                            [category_nicename] => lonado-9x3
                            [category_parent] => 9
                        )

                )

        )

)
*/