# Nautical Chart Indexes

**URL:** <https://community.thinkgeo.com/t/nautical-chart-indexes/9522>\
**Category:** WPF\
**Created:** [May 31, 2019, 3:20pm UTC](https://community.thinkgeo.com/t/nautical-chart-indexes/9522 "2019-05-31T15:20:05Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![vincent\_zhang](https://community.thinkgeo.com/letter_avatar_proxy/v4/letter/v/3ab097/32.png) [@vincent\_zhang](https://community.thinkgeo.com/u/vincent_zhang)\
**Post date:** [June 14, 2019, 10:20am UTC](https://community.thinkgeo.com/t/nautical-chart-indexes/9522/9 "2019-06-14T10:20:29Z")

</div>

Hi Kev,

## After we dig into the code further, we have made more improvements in memory and performance for BuildIndex method. Now we can keep the memory stable and under a reasonable/accept level. For performance, we improve some by increasing the usage of CPU. Here is the new test result on our side. The latest version is [11.0.0-beta012](https://www.nuget.org/packages/ThinkGeo.MapSuite.Layers.NauticalCharts/11.0.0-beta012).

US4FL12M.000 (0.25Mb):  
Time (11.0.0-beta010): 4.81s  
Time (11.0.0-beta011): 3.1s  
Time (Latest): 2.25s

Peek Memory (11.0.0-beta011): 0.04GB  
Peek Memory (Latest): 0.02GB

## Peek CPU (Latest): 39%

US5FL49M.000 (0.47Mb):  
Time (11.0.0-beta010): 10.369s  
Time (11.0.0-beta011): 4.059s  
Time (Latest): 4.32s

Peek Memory (11.0.0-beta011): 0.06GB  
Peek Memory (Latest): 0.03GB

## Peek CPU (Latest): 59%

US4FL18M.000 (1.04Mb):  
Time (11.0.0-beta010): 69.665s  
Time (11.0.0-beta011): 13.116s  
Time (Latest): 42.4s

Peek Memory (11.0.0-beta011): 0.17GB  
Peek Memory (Latest): 0.07GB

## Peek CPU (Latest): 83%

US3GC06M.000 (1.49Mb):  
Time (11.0.0-beta010): 181.173s  
Time (11.0.0-beta011): 61.167s  
Time (Latest): 57.7s

Peek Memory (11.0.0-beta011): 0.49GB  
Peek Memory (Latest): 0.11GB

## Peek CPU (Latest): 90%

US4FL14M.000 (2.40Mb):  
Time (11.0.0-beta010): 339.822s  
Time (11.0.0-beta011): 37.4s  
Time (Latest): 122.9s

Peek Memory (11.0.0-beta011): 0.37GB  
Peek Memory (Latest): 0.18GB

## Peek CPU (Latest): 91%

US5AK4JM.000 (4.97Mb):  
Time (11.0.0-beta010): 695.392s  
Time (11.0.0-beta011): 230.263s  
Time (Latest): 319.5s

Peek Memory (11.0.0-beta011): 0.84GB  
Peek Memory (Latest): 0.37GB

## Peek CPU (Latest): 94%

Maybe you are curious why we have to build the .hyr file, according to the .000 file. Here are the reasons:  
• ThinkGeo Nautical Charts SDK strictly follows the specification from IHO [https://www.iho.int/iho\_pubs/draft\_pubs/S-52\_e6.1.0/S-52\_e6.1.0\_and\_PresLib\_e4.0.0.htm](https://www.iho.int/iho_pubs/draft_pubs/S-52_e6.1.0/S-52_e6.1.0_and_PresLib_e4.0.0.htm). It’s rich in the symbols and you can easily to switch between different modes, show or hide different features, according to your requirements. To support so many different, complicated but colorful symbols, all are calculated and drawn on the fly, thus performance consumed. So we analysis all features in the \*.000 and create the drawing instructions of each feature in BuildIndex method, there it has some geometry processing codes, so a bit slow when building the index, but the good news is that you will experience a pretty good drawing performance when showing them up in the application. You just need to build the index only once. I’m not sure whether you tried the same product from ArcGIS, we have a much better drawing performance.

Regards,

Vincent

---

_[View the full topic](https://community.thinkgeo.com/t/nautical-chart-indexes/9522)._