All I needed to do was set the layer blend mode to "Multiply" to get rid of the background but still keep the tree and shadow.

我所需要做的是把图层的混合模式改为“正片叠底”，通过这种方式来在保留树及其阴影的同时去掉背景。

youdao

Basically, the attribute values are read off the instance element and copied to the right places in the shadow tree.

基本上是把属性值从实例元素中读出，并复制到影像树中的适当位置。

youdao

So here my element pastes the text label in the shadow tree, and stays in sync with the label at all times.

这里元素用于粘贴影像树中的标签，并随时保持标签的同步。

youdao

In other photos, a wreath in the shape of a Christmas tree dangles above highway construction, and a "Happy Holidays" banner casts its shadow on a highway empty except for a single truck.

WSJ: rom Lee Friedlander at Janet Borden Gallery