# Refinement question

**URL:** <https://community.cesium.com/t/refinement-question/9055>\
**Category:** CesiumJS\
**Created:** [February 6, 2020, 3:14pm UTC](https://community.cesium.com/t/refinement-question/9055 "2020-02-06T15:14:51Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![cguedas](https://sea2.discourse-cdn.com/cesium/user_avatar/community.cesium.com/cguedas/32/2017_2.png) [@cguedas](https://community.cesium.com/u/cguedas)\
**Post date:** [February 6, 2020, 3:14pm UTC](https://community.cesium.com/t/refinement-question/9055/1 "2020-02-06T15:14:51Z")

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**1. A concise explanation of the problem you’re experiencing.**

I have a tileset containing a hierarchy of 3 tiles : root -\> child -\> granchild.

I have 3 different models - let’s call them “big”, “medium” and “small”.

“big” should be visible in the root tile, “medium” in the child tile, and “small” in the grand-child tile.

I generated 3 b3dm files, one for each model, and associated them to the corresponding level in the tileset, and used the “ADD” refine mode.

-\> It works fine.

Now, I have more detailed versions of my “big” and “medium” models, and I want them to appear in the grand-child tile instead of the base models.

-\> I replaced the “grand-child.b3dm” with a b3dm that contains the “small” model + the detailed versions of “big” and “medium”

-\> The root tile still has “ADD” refine mode, as “child” will add more data to it

-\> The child tile now has “REPLACE” refine mode, as “grand-child” should replace its content.

When fully zoomed in, I correctly see the “small” model + the detailed version of the “medium” model.

However, for the “big” model, I can see both the base version, and the detailed one: it seems that the grand-child tile replaced the content of the child tile, but not of the root tile. Is it the intended behaviour ?

**3. Context. Why do you need to do this? We might know a better way to accomplish your goal.**

I have buildings with low-res and hi-res models. When seen from afar, I want only of the low-res models of the bigger buildings to be visible, then show more and more buildings (still low-res versions) as I zoom in, thus I want to use ADD refine mode.

Then, when I’m close enough, I want to replace all these low-res models with the hi-res ones. How can this be done ?

**4. The Cesium version you’re using, your operating system and browser.**

Cesium 1.65, Windows 10 / Ubuntu 18.04, Chrome 76 / FF 72

**Thanks for your help !**