Scene.prototype.pickRegion = function(topLeftWindowPosition, bottomRightWindowPosition) {
        //>>includeStart('debug', pragmas.debug);
        if(!defined(topLeftWindowPosition)) {
            throw new DeveloperError('topLeftWindowPosition is undefined.');
        }

        if(!defined(bottomRightWindowPosition)) {
            throw new DeveloperError('bottomRightWindowPosition is undefined.');
        }
        //>>includeEnd('debug');

        var minX = Math.min(topLeftWindowPosition.x, bottomRightWindowPosition.x);
        var maxX = Math.max(topLeftWindowPosition.x, bottomRightWindowPosition.x);

        var minY = Math.min(topLeftWindowPosition.y, bottomRightWindowPosition.y);
        var maxY = Math.max(topLeftWindowPosition.y, bottomRightWindowPosition.y);

        topLeftWindowPosition.x = minX;
        topLeftWindowPosition.y = minY;

        bottomRightWindowPosition.x = maxX;
        bottomRightWindowPosition.y = maxY;

        var context = this._context;
        var us = context.uniformState;
        var frameState = this._frameState;

        var drawingBufferPositionTopLeft = SceneTransforms.transformWindowToDrawingBuffer(this, topLeftWindowPosition, scratchPosition);
        var drawingBufferPositionBottomRight = SceneTransforms.transformWindowToDrawingBuffer(this, bottomRightWindowPosition, scratchPosition2);

        drawingBufferPositionBottomRight.y = this.drawingBufferHeight - drawingBufferPositionBottomRight.y;
        drawingBufferPositionTopLeft.y = this.drawingBufferHeight - drawingBufferPositionTopLeft.y;

        var drawingBufferPositionMiddle = new Cartesian2((drawingBufferPositionTopLeft.x + drawingBufferPositionBottomRight.x)*0.5, (drawingBufferPositionTopLeft.y + drawingBufferPositionBottomRight.y)*0.5);

        if (!defined(this._pickFramebuffer)) {
            this._pickFramebuffer = context.createPickFramebuffer();
        }

        var rectangleWidth = Math.abs(drawingBufferPositionTopLeft.x - drawingBufferPositionBottomRight.x);
        var rectangleHeight = Math.abs(drawingBufferPositionTopLeft.y - drawingBufferPositionBottomRight.y);

        if (rectangleWidth<3) {
            rectangleWidth = 3;
        }

        if (rectangleHeight<3) {
            rectangleHeight = 3;
        }

        // Update with previous frame's number and time, assuming that render is called before picking.
        updateFrameState(this, frameState.frameNumber, frameState.time);
        //frameState.cullingVolume = getPickCullingVolume(this, drawingBufferPositionMiddle, rectangleWidth, rectangleHeight);
        frameState.passes.pick = true;

        us.update(context, frameState);

        this._commandList.length = 0;
        updatePrimitives(this);
        createPotentiallyVisibleSet(this);

        var scratchRectangle = new BoundingRectangle(drawingBufferPositionTopLeft.x, drawingBufferPositionTopLeft.y, rectangleWidth, rectangleHeight);

        executeCommands(this, this._pickFramebuffer.begin(scratchRectangle), scratchColorZero, true);
        var result = this._pickFramebuffer.endWithRect(scratchRectangle);
        context.endFrame();
        callAfterRenderFunctions(frameState);


        return result;
    };