MalaGIS

Sharing GIS Technologies, Resources and News.

When conducting multi-factor overlay analysis or multi-index comprehensive evaluation, a common preliminary step is to standardize a collection of raster layers from various sources to a uniform 0 to 1 range. This normalization facilitates subsequent weighted overlay procedures. Theoretically, a simple linear rescaling based on the minimum and maximum values of each raster should yield results exactly between 0 and 1.

However, many users encounter a perplexing issue when using tools like QGIS's Raster Rescale tool, the Raster Calculator, or GDAL's gdal_translate command. The resulting raster's minimum and maximum values are almost, but not quite, 0 and 1. For instance, you might expect a range of 0 to 1, but the actual statistics show values like 0.006 to 0.88, or 0 to 0.99999999999999. This discrepancy can be unsettling. Drawing insights from a relevant discussion on GIS Stack Exchange, this article explores the underlying reasons for this issue and presents a more reliable workflow.

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As a GIS professional, who hasn't been driven mad by the manual georeferencing of historical imagery? When rushing to meet project deadlines, the author often had to hunch over the screen, scrutinizing scanned maps for control points — they had to be "timeless" features like road intersections, bridges, or landmark buildings. If the old map was blurry or the landmark had been demolished, it meant digging through archives all over again. Then, switching to ArcGIS, we would painstakingly align points one by one against a reference basemap, manually inputting latitude and longitude coordinates. Each point had to be checked three times, fearing a single entry error could throw the entire map out of alignment. What's even more torturous is that too few control points compromise accuracy, while too many can introduce distortion. And when batch-processing aerial photos? That meant burning the midnight oil in front of the computer, repeating the tedious operations until your fingers trembled.

The scene described by the author is sure to send shivers down the spines of many, a true nightmare. However, in 2026, AI is finally starting to save (or take over the jobs of) GIS drafters. In a previous article, "QGIS Map Georeferencing Tutorial (with AI)", the author introduced an AI georeferencing plugin for QGIS, but its performance was somewhat lacking. Recently, @yaoyao, author of Kongtian Perception, recommended a tool to the author: georeferencer.ai. Let's take a look at it today.

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Recently, while working on an offline map deployment project, I found that the transfer efficiency was relatively low and offline deployment cumbersome when dealing with massive amounts of scattered tile files. Initially, I considered using a ZIP package for transfer and extraction, but later discovered that a format already existed which implements this concept and does so even better: MBTiles. MBTiles is a map tile storage specification based on an SQLite database. It packages thousands of independent map tiles (PNG, JPG, or vector PBF) into a single .mbtiles file.

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A few days ago, while processing some legacy DWG files left by the previous data team in QGIS, I was reminded of the company's AutoCAD replacement project from three years ago. That project, based on a open-source CAD software, was ultimately shelved due to the high costs of complex development. It got me thinking: it's already 2026, how have open-source CAD software options evolved? Are there any outstanding open-source alternatives? With these questions in mind, I searched some information. If you have other better recommendations, feel free to leave a comment for discussion.

FreeCAD

FreeCAD is currently one of the most popular open-source 3D CAD software, released under the LGPL license. It is suitable for fields like engineering, architectural design, mechanical design, and product design. Its core feature is parametric modeling, where all design elements are defined by parameters and formulas. When a parameter is changed, all dependent design elements update automatically. It comes with many features and tools for professional applications, including part design, assembly, motion simulation, material property management for mechanical engineering, and supports BIM (Building Information Modeling) workflows.

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In the previous article QGIS 4.0 Delayed: New Release Scheduled for February 2026, the editor introduced the latest progress on QGIS 4.0 development, noting that the originally planned QGIS 4.0 version has been postponed to February 2026. This is very disappointing news for many macOS users, especially those with M-series chips, as everyone has been waiting for the official native QGIS application for Mac M chips. Consequently, users will have to continue using the translated version of QGIS (which still works). However, there is good news: the official team has ported the Mac packaging method originally intended for QGIS 4.0 to the QGIS 3.x series. This means that an official native QGIS 3.x version for Mac M chips is now available. The editor checked today and confirmed that the official website has been updated. Users still on the Intel-translated version are highly recommended to upgrade immediately!

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In the previous article, QGIS 4.0 Roadmap Unveiled: Major Qt6 Migration Scheduled for October Release, we introduced some early news about QGIS 4.0. According to the official roadmap, QGIS 4.0 (based on Qt 6) was expected to be released in October 2025—around this time. However, upon checking the official website yesterday, it appears that QGIS 4.0 has been officially delayed, with the new release date now set for February 2026.

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In the previous article, A Guide to Using Jilin-1 Satellite Imagery as a Basemap in ArcGIS Pro, I introduced the Jilin-1 basemap service as an alternative to China’s Tianditu maps for ArcGIS Pro users. Many readers asked whether there are other map sources available. Today, let’s look at another excellent basemap provider — Geovis Earth.

PS: I’ve actually mentioned Geovis Earth several times in earlier posts. Back then, with so many international basemap options, few paid attention. However, after ArcGIS Pro Services Blocked in China? Chinese Users Are in Trouble..., the number of stable and accessible basemap services in China has significantly decreased. In this context, Geovis Earth has become a great alternative.

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Following recent announcements from the Ministry of State Security and the service suspension of ArcGIS Pro basemaps, many users have suggested switching to QGIS. However, does using QGIS truly ensure security and compliance? After several days of research, this article attempts to explore this issue and welcomes further discussion.

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On September 10, 2025, the National Forestry and Grassland Administration (NFGA) announced Notice No. 12 of 2025, officially approving the establishment of the Huangyan Island National Nature Reserve. In accordance with the relevant provisions of the "Regulations of the People's Republic of China on Nature Reserves," the area, scope, and functional zoning of the Huangyan Island National Nature Reserve are hereby published. The reserve is located in Sansha City, Hainan Province, covering a total area of 3,523.67 hectares. This includes a core zone of 1,242.55 hectares and an experimental zone of 2,281.12 hectares. The primary conservation objective is the coral reef ecosystem. The main areas are shown in the figure below:

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In the previous article titled "Displaying Selected Layer Count in QGIS with PyQGIS - MalaGIS", the author introduced a method to quickly view the number of selected layers using QGIS's Python API. However, if you need this functionality, you must open QGIS, then open the Python Console, locate the saved Python script file, and run it every single time. Although this process is simple, it can become tedious after repeated use. So, is there a way to automatically run a Python script when QGIS starts up? The author searched online and finally found a temporarily viable method to share today.

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