def startRender(self, scene, cam): # start render in a new thread self.renderTask = RenderThread(self.width, self.height, scene, cam) self.renderTask.updateImgSignal.connect(self.updateRenderImage) self.renderTask.bucketProgressSignal.connect(self.showBucketProgess) self.renderTask.finished.connect(self.cleanBucketLocators) self.renderTask.finished.connect(self.saveImage) self.renderTask.start()