同意曹老师的解答，但我有一个疑问。

我经常看到曹老师这样注解than 及其后面的意思：

This will lead to a far greater diversity of urban landscape designs compared with the urban landscape designs that are apparent today.

据我所知，过去分词短语compared with 虽然表示比较意义，但句中不需出现比较级形式，也就是说，不需出现-er 或more 的字眼。例如：

This is fearfully expensive compared with the last one I bought. 

这和我上次买的相比贵得吓人。

来自柯林斯例句

The room was light and lofty compared with our Tudor ones. 

跟我们都铎风格的房间比起来，这个房间显得素雅而大气。

来自柯林斯例句

Life was now drab compared with the more exciting life style overseas.

比起海外那种更富有刺激的生活方式来,现在的生活显得了无生气。

来自《简明英汉词典》

我的疑问是：

这是不是Huddleston CGEL 的解释？

在有比较级的情况下，compared with 能否取代than？

This will lead to a far greater diversity of urban landscape designs than are apparent today.

参考翻译：这将产生一个远远丰富于今日显而易见的的城市景观设计多样性。

解答如下：

比较对象为“diversity of urban landscape”从句不可以在加主语，从句主语空缺位被than填充

greater diversity of urban landscape designs 与many diversity of urban landscape design 进行比较

从句从比较连接代词取代了many diversity of urban landscape designs

备注：同意刘老师，compared with A,  B do sth,  B分句不需要用比较级形式

Compared with French,English is easy.

=When English is compared with French, it is easy.
英语比法语好学/与法语相比，英语容易学。

Compared with what he had already, the new stamps were not very interesting.
跟他已有的相比,这几张新邮票算不上有趣。