caffe版SSD配置注意问题

论文作者在原版caffe基础上加上了一些别的操作和方法来实现SSD，所以配置caffe时遇到了很多官方caffe 没有的问题，例如src/caffe/util/中的math_functions.cpp文件中的caffe_rng_uniform函数写的不完善，不注释掉’CHECK_LE(a, b)’，则会出现Check failed: a <= b <0 vs -1.19209e-007>错误，注释掉的话，后面训练会出现Data layer prefetch queue empty错误，网上有几个方法来解决这个问题，其中一个是修改caffe_rng_uniform函数如下：

void caffe_rng_uniform(const int n, Dtype a, Dtype b, Dtype* r) {
  CHECK_GE(n, 0);
  CHECK(r);
  if(a > b) {
    Dtype c = a;
    a = b;
    b = c;
  }
  CHECK_LE(a, b);
  boost::uniform_real<Dtype> random_distribution(a, caffe_nextafter<Dtype>(b));
  boost::variate_generator<caffe::rng_t*, boost::uniform_real<Dtype> >
      variate_generator(caffe_rng(), random_distribution);
  for (int i = 0; i < n; ++i) {
    r[i] = variate_generator();
  }
}

另外一种是修改src/caffe/util/sampler.cpp，如下面修改代码所示//renew注释下，加入两个判断，使得bbox长宽不要越界。

void SampleBBox(const Sampler& sampler, NormalizedBBox* sampled_bbox) {
  // Get random scale.
  CHECK_GE(sampler.max_scale(), sampler.min_scale());
  CHECK_GT(sampler.min_scale(), 0.);
  CHECK_LE(sampler.max_scale(), 1.);
  float scale;
  caffe_rng_uniform(1, sampler.min_scale(), sampler.max_scale(), &scale);
 
  // Get random aspect ratio.
  CHECK_GE(sampler.max_aspect_ratio(), sampler.min_aspect_ratio());
  CHECK_GT(sampler.min_aspect_ratio(), 0.);
  CHECK_LT(sampler.max_aspect_ratio(), FLT_MAX);
  float aspect_ratio;
  caffe_rng_uniform(1, sampler.min_aspect_ratio(), sampler.max_aspect_ratio(),
      &aspect_ratio);
 
  aspect_ratio = std::max<float>(aspect_ratio, std::pow(scale, 2.));
  aspect_ratio = std::min<float>(aspect_ratio, 1 / std::pow(scale, 2.));
 
  // Figure out bbox dimension.
  float bbox_width = scale * sqrt(aspect_ratio);
  float bbox_height = scale / sqrt(aspect_ratio);
 
  //renew
  if(bbox_width>=1.0)
  {
    bbox_width=1.0;
  }
  if(bbox_height>=1.0)
  {
    bbox_height=1.0;
  }
 
  // Figure out top left coordinates.
  float w_off, h_off;
  caffe_rng_uniform(1, 0.f, 1 - bbox_width, &w_off);
  caffe_rng_uniform(1, 0.f, 1 - bbox_height, &h_off);
 
  sampled_bbox->set_xmin(w_off);
  sampled_bbox->set_ymin(h_off);
  sampled_bbox->set_xmax(w_off + bbox_width);
  sampled_bbox->set_ymax(h_off + bbox_height);
}

参考：
https://blog.youkuaiyun.com/LuohenYJ/article/details/88416180

https://ask.youkuaiyun.com/questions/7078439