这是因为，在单元格大小可以自动计算之前为零，因此约束崩溃。
This is because, before the cell size can be calculated automatically it is zero, so the constraints crash.
第一个参数（1000）以米为单位指定网格单元格大小，因为米是与 location 列相关联的 SRS 的直线单位。
The first parameter (1000) specifies the grid cell size in meters, because that is the linear unit of the SRS associated with the location column.
与表格单元格、行和列一样，当您未明确设置图像大小时，浏览器需要执行计算来显示图像，这会降低处理速度。
As with table cells, rows, and columns, when you don't explicitly set the image size, the browser needs to perform calculations to display the image, which slows down processing.
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