Microsoft 认知服务视觉 API ClientException 错误

我正在尝试使用视觉认知服务来接收图像的描述，但我的代码总是抛出此异常：

Exception Microsoft.ProjectOxford.Vision.ClientException
HResult=0x80131500
Origine=<Non è possibile valutare l'origine dell'eccezione>
Stack:
in Microsoft.ProjectOxford.Vision.VisionServiceClient.HandleException (Exception exception)
in Microsoft.ProjectOxford.Vision.VisionServiceClient.<SendAsync>b__42_1[TRequest,TResponse](Exception e)
in System.AggregateException.Handle(Func`2 predicate)
in Microsoft.ProjectOxford.Vision.VisionServiceClient.<SendAsync>d__42`2.MoveNext()
in System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
in System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
in Microsoft.ProjectOxford.Vision.VisionServiceClient.<AnalyzeImageAsync>d__21`1.MoveNext()
in System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
in System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
in Microsoft.ProjectOxford.Vision.VisionServiceClient.<AnalyzeImageAsync>d__20.MoveNext()
in System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
in System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
in System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
in CognitiveServices.MainPage.<Button_Clicked>d__1.MoveNext() in C:\Users\manu9\documents\visual studio 2017\Projects\CognitiveServices\CognitiveServices\CognitiveServices\MainPage.xaml.cs: riga 48

这是我的代码：

using Microsoft.ProjectOxford.Vision;
using Microsoft.ProjectOxford.Vision.Contract;
using Plugin.Media;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;

namespace CognitiveServices
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private async void Button_Clicked(object sender, EventArgs e)
        {
            var media = Plugin.Media.CrossMedia.Current;
            await media.Initialize();
            var file = await media.TakePhotoAsync(new Plugin.Media.Abstractions.StoreCameraMediaOptions
            {
                SaveToAlbum = false
            });
            image.Source = ImageSource.FromStream(() => file.GetStream());

            var visionClient = new VisionServiceClient("MY_API_KEY");

            var visualFeats = new VisualFeature[]
            {
                VisualFeature.Description, 
                VisualFeature.Faces
            };

            Stream imagestream = file.GetStream();
            imagestream.Seek(0, SeekOrigin.Begin);

            var result = await visionClient.AnalyzeImageAsync(imagestream, visualFeats);
            description.Text = result.Description.Captions.First().Text;

            Debug.WriteLine(result.Description.Captions[0].Text);
            file.Dispose();
        }
    }
}

为什么我总是出现这个异常？我读到有人通过添加类似的内容解决了这个问题imageStream.Seek(0)这是真的吗？

您的 API 密钥很可能与您正在访问的端点不对应。如果你看一下客户端的源代码 https://github.com/Microsoft/Cognitive-Vision-Windows/blob/master/ClientLibrary/VisionServiceClient.cs#L58你会看到默认情况下它会到达美国西部（https://westus.api.cognitive.microsoft.com/vision/v1.0）并且您的密钥可能与另一个区域相对应（就像我的情况一样）。

You can change this by doing new VisionServiceClient(apiKey, apiRoot), where apiRoot is obtained through the Azure Portal:

在我的例子中输出的工作代码Satya Nadella wearing glasses and smiling at the camera.

using Microsoft.ProjectOxford.Vision;
using Microsoft.ProjectOxford.Vision.Contract;
using System;
using System.Configuration;
using System.IO;

namespace VisionClient
{
    public class Program
    {
        public static void Main(string[] args)
        {
            AnalyzeImage();
            Console.WriteLine("Press any key to exit...");
            Console.ReadLine();
        }

        private static void AnalyzeImage()
        {
            var apiKey = ConfigurationManager.AppSettings["VisionApiSubscriptionKey"];
            var apiRoot = "https://eastus2.api.cognitive.microsoft.com/vision/v1.0";
            var visionClient = new VisionServiceClient(apiKey, apiRoot);

            var visualFeats = new VisualFeature[]
            {
                VisualFeature.Description,
                VisualFeature.Faces
            };

            Stream imageStream = File.OpenRead("satyaNadella.jpg");

            try
            {
                AnalysisResult analysisResult = visionClient.AnalyzeImageAsync(imageStream, visualFeats).Result;
                foreach(var caption in analysisResult.Description.Captions)
                {
                    Console.WriteLine("Description: " + caption.Text);
                }
            }
            catch (ClientException e)
            {
                Console.WriteLine("Vision client error: " + e.Error.Message);
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: " + e.Message);
            }
        }
    }
}