安卓Arcore識別測距

    背景：需要識別物體，並且測量物體的尺寸
    思路：

識別物體

1、百度雲，阿里雲等有很多識別，如果有API識別，就用吧，比較容易，具體接入可以看官方文檔

2、另外一種方式就是opencv分析了。這一點我也在研究，我現在識別的代碼就不貼了。
 

物體尺寸測量
由於我們是根據圖片識別物體，所以返回的是某一幀的圖片上的像素點A（x1，y1）到B（x2，y2）。要轉換成空間座標系的點。再計算距離。這裏我用的基於安卓的Arcore來實現的。

好吧，廢話不多說，上代碼，獲取某一幀圖，然後發送給識別檢測的服務器
在Activity中

arFragment.getArSceneView().getScene().addOnUpdateListener(this::onUpdateFrame);

onUpdataFrame：

發送請求用的是okhttputil，在github上面搜一下就知道了
第一步：frame.acquireCameraImage();獲得某一幀圖片
第二步：OkHttpUtils.post()發送請求
第三步：List<HitResult> hitResults1 = arFragment.getArSceneView().getArFrame().hitTest(positionResults.getPositionResults().get(0).getX(), positionResults.getPositionResults().get(0).getY()); 根據返回的像素點得到空間碰撞的HitResults
第四步： showDistance(hitResults1.get(0), hitResults2.get(0));展示距離吧

private void onUpdateFrame(FrameTime frameTime) {
    Frame frame = arFragment.getArSceneView().getArFrame();
    // If there is no frame, just return.
    if (frame == null) {
        return;
    }

Image image = null;
try {
    image = frame.acquireCameraImage();
    Bitmap bitmap = imageToBitmap(image);
    if (bitmap != null) {
        File file = getFile(bitmap);
        OkHttpUtils.post()
                .addFile("file", "pic" + imageIndex + ".png", file)//
                .url("xxxxx")
                .build()
                .execute(new Callback() {
                    @Override
                    public Object parseNetworkResponse(Response response, int id) throws Exception {
                        try {
                            String str = response.body().string();
                            positionResults = new Gson().fromJson(str, PositionResults.class);
                            return positionResults;
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        return null;
                    }
                    @Override
                    public void onError(Call call, Exception e, int id) {
                        System.out.println("error!!!!!");
                    }
                    @Override
                    public void onResponse(Object response, int id) {
                        System.out.println("response");
                    }
                });
                        List<HitResult> hitResults1 = arFragment.getArSceneView().getArFrame().hitTest(positionResults.getPositionResults().get(0).getX(),
                                positionResults.getPositionResults().get(0).getY());
                        List<HitResult> hitResults2 = arFragment.getArSceneView().getArFrame().hitTest(positionResults.getPositionResults().get(1).getX(),
                                positionResults.getPositionResults().get(1).getY());
                        if (hitResults1.size() > 0 && hitResults2.size() > 0) {
                            showDistance(hitResults1.get(0), hitResults2.get(0));
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
//                    sendFlag=true;
                if (null != image) {
                    image.close();
                }
            }

showDistance：

private void showDistance(HitResult hitResult1, HitResult hitResult2) {
    Anchor anchor1 = hitResult1.createAnchor();
    AnchorNode firstAnchorNode = new AnchorNode(anchor1);

    Anchor anchor2 = hitResult2.createAnchor();
    AnchorNode secondAnchorNode = new AnchorNode(anchor2);
    secondAnchorNode.setParent(arFragment.getArSceneView().getScene());

    double ddx = (firstAnchorNode.getWorldPosition().x - secondAnchorNode.getWorldPosition().x);
    double ddy = (firstAnchorNode.getWorldPosition().y - secondAnchorNode.getWorldPosition().y);
    double ddz = (firstAnchorNode.getWorldPosition().z - secondAnchorNode.getWorldPosition().z);

    float ndl = (float) Math.sqrt(ddx * ddx + ddy * ddy + ddz * ddz);

Toast toast1 =
        Toast.makeText(this, "dl is" + dl + "M,firstV:(" + firstV.x + "," + firstV.y + "," + firstV.z + "),secendV:("
                        + secondV.x + "," + secondV.y + "," + secondV.z + ")",
                Toast.LENGTH_LONG);
toast1.setGravity(Gravity.CENTER, 0, 0);
toast1.show();

」

但是這樣還是不夠直觀，所以在兩點之間畫根直線吧

private void addLineBetweenPoints(Scene scene, Vector3 from, Vector3 to) {
    // prepare an anchor position
    Quaternion camQ = scene.getCamera().getWorldRotation();
    float[] f1 = new float[]{to.x, to.y, to.z};
    float[] f2 = new float[]{camQ.x, camQ.y, camQ.z, camQ.w};
    Pose anchorPose = new Pose(f1, f2);

    // make an ARCore Anchor
    Anchor anchor = arFragment.getArSceneView().getSession().createAnchor(anchorPose);
    // Node that is automatically positioned in world space based on the ARCore Anchor.
    AnchorNode anchorNode = new AnchorNode(anchor);
    anchorNode.setParent(scene);

    // Compute a line's length
    float lineLength = Vector3.subtract(from, to).length();

    // Prepare a color
    Color colorOrange = new Color(android.graphics.Color.parseColor("#ffa71c"));

    // 1. make a material by the color
    MaterialFactory.makeOpaqueWithColor(this, colorOrange)
            .thenAccept(material -> {
                // 2. make a model by the material
                ModelRenderable model = ShapeFactory.makeCylinder(0.0025f, lineLength,
                        new Vector3(0f, lineLength / 2, 0f), material);
                model.setShadowReceiver(false);
                model.setShadowCaster(false);

                // 3. make node
                Node node = new Node();
                node.setRenderable(model);
                node.setParent(anchorNode);

                // 4. set rotation
                final Vector3 difference = Vector3.subtract(to, from);
                final Vector3 directionFromTopToBottom = difference.normalized();
                final Quaternion rotationFromAToB =
                        Quaternion.lookRotation(directionFromTopToBottom, Vector3.up());
                node.setWorldRotation(Quaternion.multiply(rotationFromAToB,
                        Quaternion.axisAngle(new Vector3(1.0f, 0.0f, 0.0f), 90)));
            });
}

 

完成！