Tiny-object detectors stop guessing query counts: BUTR sets the budget from encoder confidence, reaching 35.7 AP with 316 queries on AI-TOD-v2
In dense tiny-object detection, dynamic query designs previously entangled how many queries are decoded with which queries are kept, obscuring the source of gains. BUTR reframes dynamic query as allocating decoder query budget by object density: it sums encoder proposal confidences into a density proxy and maps it linearly to a per-image query count, keeping standard Top-k initialization without learned modules or heuristic filtering. On AI-TOD-v2, BUTR-L reaches 35.7 AP with 316 queries on average, versus 35.2 AP and 600 queries for same-scale D-FINE-L.