AR 参考图像 - 图像的直方图很窄 [英] AR Reference image - The histogram of the image is narrow

问题描述

我正在将图像添加到 ARKit 项目中.但它给出了错误.

解决方案

您的图像内容不适合检测.WWDC18 演讲中有

右侧的图像有多个问题，但也有您遇到的统一颜色区域"和窄直方图"问题.对于人类来说，该图像很容易识别，因为它使用我们识别空背景上的实体形状的能力——不过，这种能力显然不是计算机视觉算法的强项.相反，您正在寻找大量细节——图像范围内具有高局部对比度的许多点.此外，您正在以灰度和低分辨率查看它，因为您希望在移动设备上以 60 fps 的速度运行.

这是左侧图像的直方图(转换为灰度后):

这是右侧图像的直方图(同样):

直方图是一种量化好图像具有许多亮度等级的方法，而坏图像则有大块，只有几个不同的灰色阴影——你想要前者.

I am adding an image into ARKit project. But it gives error.

解决方案

You have an image whose content is not good for detection. There's a section in the WWDC18 talk What's New in ARKit 2 that talks about this and has some examples of what's good and what's not:

The image on the right has multiple problems, but shares the "uniform color regions" and "narrow histogram" issues you have. For a human, that image is pretty easy to recognize, because it uses our ability to identify solid shapes on empty backgrounds — that ability apparently isn't a strength of the computer vision algorithm in play here, though. Instead, you're looking for lots of detail — many points across the extent of the image with high local contrast. Also, you're looking at it in grayscale and at low resolution because you want to run at 60 fps on a mobile device.

Here's the histogram of the image on the left (after converting to grayscale):

Here's the histogram of the image on the right (likewise):

The histograms are a way of quantifying that the good image has lots of gradations of brightness, where the bad image has large chunks of only a few distinct shades of gray — you want the former.

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