DeepSeek智能時空數據分析（八）：NL2SQL繪制河流-軌跡緩沖區如何生成

序言：時空數據分析很有用，但是GIS/時空數據庫技術門檻太高

時空數據分析在優化業務運營中至關重要，然而，三大挑戰仍制約其發展：技術門檻高，需融合GIS理論、SQL開發與時空數據庫等多領域知識；空間數據缺乏直觀可視化工具，導致分析結果難以高效傳達；現有產品成本高昂，限制了中小企業應用。

本系列文章將借助DeepSeek等大模型的能力，通過NL2SQL等免費/低成本 AI GIS智能體能力，幫助不熟悉SQL、GIS但是有空間數據分析需求的讀者實現最常用的分析功能。

前序文章

《DeepSeek智能時空數據分析（一）：篩選特定空間范圍內的POI數據》

《DeepSeek智能時空數據分析（二）：3秒對話式搞定“等時圈”繪制》

《DeepSeek智能時空數據分析（三）：專業級地理數據可視化賞析-《杭州市國土空間總體規劃（2021-2035年）》》

《DeepSeek智能時空數據分析（四）：繪制行政區域并定制樣式
》

《DeepSeek智能時空數據分析（五）：基于區域人口數量繪制地圖散點-大模型搜集數據NL2SQL加工數據》

《DeepSeek智能時空數據分析（六）：大模型NL2SQL繪制城市之間連線》

《DeepSeek智能時空數據分析（七）：4326和3857兩種坐標系有什么區別？各自用途是什么？》

參考地理數據可視化案例

前文所述《杭州市國土空間總體規劃（2021-2035年）》（公開稿），有很多經典的行政區域繪制案例，例如：
在這里插入圖片描述
參考這個區域空間布局結構規劃圖，前序分享文章《DeepSeek智能時空數據分析（六）：大模型NL2SQL繪制城市之間連線》已經完成了大部分要素通過大模型NL2SQL進行了繪制，效果如下：

在此基礎上，本文將參考《杭州市國土空間總體規劃（2021-2035年）》-生態空間格局規劃圖中的河流要素，添加到之前的項目中：
在這里插入圖片描述

第一步：導入河流空間數據

按參考案例所示，我們需要導入一段錢塘江的流域數據，可以參考以下樣本：（復制后另存為geojson格式文件）

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或者利用GeoAtlas工具，利用畫線工具自行手工標繪一份河流數據：
在這里插入圖片描述
獲得河流空間數據之后，導入DataV Atlas數據中心：

導入數據中心之后，將河流數據加入到之前項目中：

導入完畢后，在河流數據源選擇“轉為sql查詢”，便于下一步NL2SQL處理：

第二步：大模型NL2SQL生成河流緩沖區

空間數據一般存儲用4326，顯示用3857，具體可以參考前序文章《DeepSeek智能時空數據分析（七）：4326和3857兩種坐標系有什么區別？各自用途是什么？》

因此，在平面地圖上繪制河流要素需要完成以下兩步：

將幾何對象從4326坐標系轉換到3857坐標系；
使用緩沖區函數ST_Buffer生成以幾何對象為中心、半徑為2000米的緩沖區；

所幸我們有大模型的幫助，不需要撰寫復雜的空間數據處理SQL；
打開DataV Atlas AI助手，輸入以下提示詞：

“在3857坐標系下，以這條線為中心，生成2000米為buffer的緩沖區”

在這里插入圖片描述
大模型正確理解了我們的意圖，并輸出sql代碼：

SELECT "_draw_type", "adcode", ST_Buffer(ST_Transform("geom", 3857), 1500) AS buffer_geom
FROM "public"."u0piif_hangzhou_river_01";

sql代碼含義如下：

ST_Transform(“geom”, 3857)：將geom字段的幾何對象從原始坐標系（4326）轉換到目標坐標系（3857）。
ST_Buffer(…, 200)：在3857坐標系下，以轉換后的幾何對象為中心，生成半徑為200米的緩沖區。
buffer_geom：為生成的緩沖區幾何對象定義別名。