why the cesium does not support gif?

Cesium does support GIF image files. For example, in the Billboards Sandcastle demo, the “Add multiple billboards” button loads a billboard from facility.gif.

i mean it has no dynamic effect when using gif image

在 2014年6月25日星期三UTC+8下午10时46分03秒,Scott Hunter写道:

I believe this is a WebGL limitation. When we create a texture from an image, it is always a static snapshot. http://www.khronos.org/registry/webgl/extensions/proposals/WEBGL_dynamic_texture may or may not change this someday.

A better option would be to use HTML5 video instead, which provides access to individual frames. The “video” branch in Cesium has experimental support for a CZML VideoMaterialProperty.