dme-compunet/YoloV8

Error Sequence contains no elements on image plotting

H-pun opened this issue · 3 comments

H-pun commented

Hello, I'm currently working on my API project using this library.

I use this standard code and it works perfectly fine on my computer.

using Compunet.YoloV8;
using Compunet.YoloV8.Plotting;
using SixLabors.ImageSharp;

var imagePath = "path/to/image";

using var predictor = YoloV8Predictor.Create("path/to/model");

var result = await predictor.DetectAsync(imagePath);

using var image = Image.Load(imagePath);
using var ploted = await result.PlotImageAsync(image);

ploted.Save("./pose_demo.jpg")

but when I deploy it on Cloud Run (Google Cloud Platform) it throws an error:

 System.TypeInitializationException: The type initializer for 'Compunet.YoloV8.Plotting.DetectionPlottingOptions' threw an exception.
 ---> System.InvalidOperationException: Sequence contains no elements
 at System.Linq.ThrowHelper.ThrowNoElementsException()
 at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
 at Compunet.YoloV8.Plotting.PlottingOptions.GetDefaultFontFamily()
 at Compunet.YoloV8.Plotting.PlottingOptions..ctor()
 at Compunet.YoloV8.Plotting.DetectionPlottingOptions..ctor()
 at Compunet.YoloV8.Plotting.DetectionPlottingOptions..cctor()
 --- End of inner exception stack trace ---
 at Compunet.YoloV8.Plotting.DetectionPlottingOptions.get_Default()
 at Compunet.YoloV8.Plotting.PlottingExtensions.PlotImage(DetectionResult result, ImageSelector`1 originImage)
 at Compunet.YoloV8.Plotting.PlottingAsyncOperationExtensions.<>c__DisplayClass2_0.<PlotImageAsync>b__0()
 at System.Threading.Tasks.Task`1.InnerInvoke()
 at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
 --- End of stack trace from previous location ---
 at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
 at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
 --- End of stack trace from previous location ---
 at Compunet.YoloV8.Plotting.PlottingAsyncOperationExtensions.PlotImageAsync(DetectionResult result, Image originImage)
 at Dietary.Controllers.FoodController.Predict(IFormFile imgFile) in /src/Controllers/FoodController.cs:line 65

I know it has something to do with image plotting because without the plot, the predict works perfectly fine.
Or does it have something to do with my docker?

FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
WORKDIR /app
EXPOSE 8080

ENV ASPNETCORE_URLS=http://+:8080

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY ["Dietary.csproj", "./"]
RUN dotnet restore "Dietary.csproj"
COPY . .
WORKDIR "/src/."
RUN dotnet build "Dietary.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "Dietary.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "Dietary.dll"]
dme-compunet commented
H-pun commented

You were right! it was because there were no fonts available in the container.

So i tried your solution by adding default font to my project and load it like this:
using var ploted = await result.PlotImageAsync(image, new() { FontFamily = new FontCollection().Add(fontPath) });

However, upon initialization, the PlottingOptions constructor will always invokes GetDefaultFontFamily(), which is the main problem since there are no system fonts in the first place.

public PlottingOptions()
{
    FontFamily = GetDefaultFontFamily();
    FontSize = 12f;
}

So currently my solution is by installing ttf-mscorefonts-installer for default SystemFonts on my Docker container. However, this solution is suboptimal as it could potentially degrade server performance.

RUN echo "deb http://deb.debian.org/debian/ bookworm main contrib" > /etc/apt/sources.list && \
    echo "deb-src http://deb.debian.org/debian/ bookworm main contrib" >> /etc/apt/sources.list && \
    echo "deb http://security.debian.org/ bookworm-security main contrib" >> /etc/apt/sources.list && \
    echo "deb-src http://security.debian.org/ bookworm-security main contrib" >> /etc/apt/sources.list
RUN sed -i'.bak' 's/$/ contrib/' /etc/apt/sources.list
RUN apt-get update; apt-get install -y ttf-mscorefonts-installer fontconfig

Well I think by using FirstOrDefault() in GetDefaultFontFamily() is better than First() since it wont throw Sequence contains no elements and FontFamily can be reassigned if there are no fonts available.

  • 👍1
dme-compunet commented

I'll fix it soon, thanks for reporting it.

  • 🚀1