# HoughCircles far distance

Hello,

I'm a beginner in OpenCV. I developed some apps for Android and now I want to develop an App with OpenCV4Android. First I want to detect some Circles for example Coins. I tried Threshold (with Binary or Otsu), Erode, Canny, GaussianBlur in different variations, but always my HoughCircles after all this "filters" return no circles or only some if I my camera is really near (~5cm) to the circles. But I want that it recognizes the circles also from a distance more than 30cm. I use HoughCircles like this:

int iUpperThreshold = 200;
int iMinRadius = 0;
int iMaxRadius = 0;
int iAccumulator = 100;