Using Virtual and Augmented Reality with GIS Data

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper introduces a method that combines virtual reality (VR) and augmented reality (AR) with Geographic Information Systems (GIS) data to visualize GIS information. A comprehensive workflow is outlined, encompassing tiling, DEM generation, and conversion of GeoTIFF data into 3D objects. This workflow is seamlessly integrated with Unreal Engine to provide a novel approach for immersive GIS visualization and interaction. However, several aspects require further clarification and refinement:

Firstly, This paper primarily focuses on detailing the utilization of GIS data for the purpose of realizing VR and AR technologies. However, a notable absence is the comparison with similar research works , which limits the prominence of its innovative research.

Secondly, in terms of software selection, a more detailed rationale should be provided for choosing QGIS and Unreal Engine as the primary software tools. This explanation should highlight their respective advantages compared to other available options.

Thirdly, within the text's lines 262 to 282, the conversion of data into a format compatible with Unreal Engine using the Three.js library requires a more in-depth explanation. This includes outlining the specific steps involved, highlighting key technical considerations, and discussing the potential advantages and limitations associated with this approach.

Lastly, when importing GIS data into Unreal Engine and converting it to a format compatible with the engine, there are concerns regarding the potential impact on data accuracy and resolution. Therefore, a more detailed description of the converted format and its characteristics is deemed necessary.

 

Author Response

Dear reviewer,

Thank you for your comments on the article, we have tried to implement all suggestions and questions and answer your questions. The answers are attached in a word document.

Best regards,

Karel Pavelka Jr.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present a workflow for incorporating QGIS raster data into a VR application implemented using the Unreal Engine. While the resulting application looks interesting (based on the figures in the article), it is unfortunately not entirely clear, what the purpose of this work is and what kind of tasks should be accomplished when using it.

Motivation
----------

A major issue the motivation and the goal of this work. Apparently the aim of the work was to visualise GIS data in AR and VR using a game engine. *Why* the authors want to do that is unclear and so it is also hard to evaluate if the way they accomplished this goal is useful for a particular application or for specific users. The authors focus on raster data and are completely ignoring vector data in their application, but no reason is mentioned. For related works, it is repeatedly mentioned that it does not fit the authors objectives (e.g. vor GeaVR, line 153-155, again in line 164/165, and in the conclusion, line 443-445) when it is not entirely clear what these objectives actually are. When section 3 mentions datasets used for this work, it is unclear why exactly these types of raster data are selected.
Why was the Unreal Engine selected? I'm not saying it is a bad choice but since we don't know the goal of this work, it's hard to judge if it actually is a good choice.
"The combination of QGIS and Unreal Engine presents a powerful symbiosis..." - Why is that?
When line 222-226 list the key features, it is again unclear, *why* these are key features since we don't know what the application should be used for. This extends to the details of the workflow. E.g. Why can't the users employ pyramidal loading algorithms (line 246-249) when this is frequently used in games?
Why where the Netherlands and the Czech Republic selected as areas of interest?


State of the art
----------------

While section 2 takes a rather detailed look at two commercial applications, the remaining evaluation of the state of art which covers only two short paragraphs in the introduction. The authors seem to be not aware of a wide range of works that already visualise GIS data in 3D contexts, sometimes via game engines. Here is a number of examples, there are many more out there:

* S Gu et al (2017): Virtual geographic environment for WATLAC hydrological model integration. In: Proc of 25th International Conference on Geoinformatics. IEEE Computer Society.
* C Helbig et al (2022): A game engine based application for visualising and analysing environmental spatiotemporal mobile sensor data in an urban context. Front. Environ. Sci. 19 , art. 952725
* H Lin et al., 2013. Virtual geographic environments (VGEs): a new
generation of geographic analysis tool. Earth Sci. Rev. 126, 74–84.
* K Rink et al (2020): A Virtual Geographic Environment for Multi-Compartment Water and Solute Dynamics in Large Catchments. Journal of Hydrology, Vol. 582 , art. 124507. DOI:10.1016/j.jhydrol.2019.124507
* K Rink et al (2022): An Environmental Exploration System for Visual Scenario Analysis of Regional Hydro-Meteorological Systems. Comput Graph 103, 192 - 200. DOI:10.1016/j.cag.2022.02.009
* Ö O Sen et al (2023): A Visual-Scenario-Based Environmental Analysis Approach to the Model-Based Management of Water Extremes in Urban Regions. In Proc of Workshop on Visualisation in Environmental Sciences (EnvirVis), pp 51-60, The Eurographics Association. DOI:10.2312/envirvis.20231106
* Yin L.: Integrating 3D visualization and GIS in planning education. Journal of Geography in Higher Education 34, 3 (2010), 419–438.

In addition to missing related work, there are missing citations throughout the paper for many of the examples given as well as statements and claims. Examples inclue:

* line 30-33: listing the benefits of AR and VR
* line 40-43: examples for the use of 360° cameras and them being a substitute for 3d models (which I somewhat doubt, by the way).
* line 86-88: examples for VR applications
* line 176: the Geo-harmonizer project. Apparently this is relevant for this work, so readers should be able to look it up.
* l 269/270: please city Three.js and Qgis2threejs
* l 293: Reference [17] seems to be incorrect here?
* l 402: mentions limitations of AR but only one is specified and no source is mentioned.


Workflow
--------

Section 4 details the workflow for the work presented in this article. The authors make extensive use of the Docker technology. However, it is not clear *why* the authors do that as they don't seem to take advantage of the usual benefits of docker. E.g. why is every single small task (data download, map tiling, etc.) encapsulated in a different container? Why use containers for tasks such as "download input data" at all, when there are platform-independent tools for doing that?

Why use that specific version of the Unreal Engine? Why is it considered the "best match"?

The authors have modelled a virtual room from which to access and visualise the data. Do users find that way of "interface" useful? (who are the typical users of this application?)

Why does it make sense to overlay exactly two maps? (i.e. what is the goal of this comparison?)

What is the advantage of using these maps as textures for a 3D terrain as opposed to classical GIS raster visualisation? (Again, I'm not saying it is a bad choice to do so, but it would be nice to know if there is a specific benefit of this type of visualisation in the scope of this application.)

To me, section 4.4 was confusing as AR usually has a completely different set of applications as VR and I am not sure, how using the previously described application at all in Augmented Reality. In what specific way is this application used to enhance reality, e.g. by used an iPad camera?


Minor issues
------------

* l 50/51: please fix sentence
* l 70: missing citation
* l 89: missing word
* l 176-182: what is the size and resolution of the datasets used?
* l 253: Again, what is the resolution of the data? Without that information, a tile size has not much meaning.
* l 299: some non-english words
* l 344: "beveled" meaning "tilted"?
* l 383: the end of the sentence is missing
* l 386: the beginning of the sence is missing?


References
----------

There are also a number of issues with references, most importantly the inconsistency of the format. Specifically I've noticed:
* the format of the references is inconsistent (e.g. the publication year appearing sometimes after the list of authors and sometimes at the end of the entry
* sometimes authors are divided by comma, sometimes by semikolen (and sometimes by both)
* for online references it is sometimes mentioned when the source was accessed and sometimes not
* sometimes the publication year is missing, sometimes whitespaces are missing, sometimes commas are missing

Comments on the Quality of English Language

Overall the English is acceptable. However, there are a number of typos and some of the sentences are difficult to understand (examples are mentioned in the above review). It would be good if a native speaker could proofread the text after adjustments are made.

Author Response

Dear reviewer,

Thank you for your comments on the article, we have tried to implement all suggestions and questions and answer your questions. The answers are attached in a word document.

Best regards,

Karel Pavelka Jr.

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

1. The paper provides a detailed description of the research process, but the discussion section is not clearly explained. How is the effectiveness of the method reflected? Where are the shortcomings? How can you research and improve them in the future?

2. In the conclusion section, the innovation and scientificity of this article were not clearly described. It is recommended to rewrite the conclusion section.

Author Response

Dear reviewer,

Thank you for your comments on the article, we have tried to implement all suggestions and questions and answer your questions. The answers are attached in a word document.

Best regards,

Karel Pavelka Jr.

 

 

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript deals with innovative solutions for GIS data visualization, extended with AR and VR technologies. It reads like a technical report showing interesting examples. The manuscript has certain improvement potential:

1)      The introduction is very long and could benefit from a better structure. Could you make a straight introduction out of it that points to the research gap, followed by a state-of-the art section on AR and VR applications?

2)      Is there any reason why you selected this portfolio of applications? Why are they special and do they have in common (synergies for your study outcome)?

3)      Your discussion section is not linked with any other literature. In how far does your study extend, back up or even contradict aspects on AR and VR visualization or data processing workflows that are discussed in the international research literature?  

Comments on the Quality of English Language

Moderate editing of English language required

Author Response

Response reviewer 4:

Dear reviewer, first of all, we would like to thank you for your valuable advice and comments and for the time you spent on our article.

1)    The introduction is very long and could benefit from a better structure. Could you make a straight introduction out of it that points to the research gap, followed by a state-of-the art section on AR and VR applications?

Thank you for your comment about the long introduction. The introduction has been shortened according to your recommendation and the rest moved to subsection 2.1, which deals with the current solution and similar applications. The next subsection immediately follows with a selection of the two closest applications

2)    Is there any reason why you selected this portfolio of applications? Why are they special and do they have in common (synergies for your study outcome)?

Our research is quite unique. We are mostly unique in the solution we want to implement in a game engine to make GIS Land cover data available to users inside virtual or augmented reality. This dataset is the first and testing phase for this application, the final was to create an application where using our workflow the user will be able to view any dataset and work with our application which will be freely available and allow users any intervention. This goal has been fulfilled in the project application all complete instructions for the implementation of custom datasets is freely available to interested users. 

The selected ESRI and GeaVR applications are the closest of the applications tracked, which for the most part focus on the same technologies and similar uses, each in something. The ESRI app makes good use of working with DEM model and texture (orthophoto only) and working in AR, while the GeaVR app works with flybys and motion in VR on DEM and texture. So the synergy between our research and these applications is in the display technologies and the use of DEMs within the game engine.

3)      Your discussion section is not linked with any other literature. In how far does your study extend, back up or even contradict aspects on AR and VR visualization or data processing workflows that are discussed in the international research literature?  

We have expanded the discussion to include the current market trend in XR technology, which we mention in the discussion, and we have linked the section on the use of tilings to the source and expanded this section.

In the second part of the question, each of the found studies processes data in some way and displays it using various software. We have also found a way to achieve the desired outputs. All of them share the same game engines, but data preparation is different. This type of utilization of game engines for GIS with datasets is not a widely spread study, so the literature is very limited.

The whole text has been sent for English proofreading and has thus been corrected. Thank you very much for your valuable comments.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

After careful review, I have identified a lack of innovation in your article. The article primarily discusses the combination of GIS data with virtual reality (VR) and augmented reality (AR) technologies, proposing a visualization workflow based on QGIS and Unreal Engine. However, compared to similar existing research, such as the works mentioned in the paper by Baumgartinger, Lütjens, and others, your article lacks unique theoretical contributions or innovative applications, despite utilizing the latest open-source tools and data.

Author Response

Dear reviewer, first of all, we would like to thank you for your valuable advice and comments and for the time you spent on our article.

Reviewer 2:

This paper introduces a method that combines virtual reality (VR) and augmented reality (AR) with Geographic Information Systems (GIS) data to visualize GIS information. A comprehensive workflow is outlined, encompassing tiling, DEM generation, and conversion of GeoTIFF data into 3D objects. This workflow is seamlessly integrated with Unreal Engine to provide a novel approach for immersive GIS visualization and interaction. However, several aspects require further clarification and refinement:

Firstly, This paper primarily focuses on detailing the utilization of GIS data for the purpose of realizing VR and AR technologies. However, a notable absence is the comparison with similar research works , which limits the prominence of its innovative research.

 

We added several sources that focused on data visualization using game engines. The integration of VR and AR with GIS data is a specific topic with many branches, as mentioned in the introduction. While similar studies exist, each tends to focus on slightly different aspects, making direct comparisons challenging. This study is innovative in its approach to large data handling and processing. The created tiling script allows us to divide large areas of interest into smaller tiles, for which various textures are subsequently generated. Data preparation in QGIS is automated using scripts, which are freely available for download. By following the workflow for working in the Unreal game engine, anyone can visualize their datasets and explore them in VR using the application created within the study.

Secondly, in terms of software selection, a more detailed rationale should be provided for choosing QGIS and Unreal Engine as the primary software tools. This explanation should highlight their respective advantages compared to other available options.

QGIS is a well known and widely used software that allows high-level GIS data processing. And it is open source software which could be adapted for the purpose of this study. Moreover QGIS includes a number of plugins such as QGIS2three.js, which was also used in the case study. We chose QGIS also for the reason to make it easier for possible users to process their own area of interest.

Unreal Engine allows this data to be visualised and edited, visualised and displayed using virtual reality. The Unreal Engine was chosen for the project because of the experience of working with it and its environment. Similar results could probably be achieved with the Unity game engine. Both of these engines are mostly used for visualization and custom applications for virtual and augmented

 

Thirdly, within the text's lines 262 to 282, the conversion of data into a format compatible with Unreal Engine using the Three.js library requires a more in-depth explanation. This includes outlining the specific steps involved, highlighting key technical considerations, and discussing the potential advantages and limitations associated with this approach.

 

We have modified the paragraph so we believe that the described technical solution is more specific. The ModelExporter class has been used to convert TIFF to glTF . The advantage is the possibility to process all tiles associated with a given area of interest. The solution depends on QGIS and the Qgis2three.jsp plugin and its API, which may change over time. Modified text below:

The Qgis2three.js plugin allows to generate a 3D model from a DEM with various settings. The suitable settings of all parameters were tested. Based on the experiments a customized script was developed by the authors to automate the whole process of generation of 3D objects from input DEM data layers. The script is using QGIS API to load an input TIFF file to a QGIS project. In the next step the loaded raster data layer is converted using Qgis2three.js API (ModelExporter class) to a 3D object in glTF format. The source code including used settings is available from the Git repository [26]. From the user perspective, the script was integrated as a macro which is launched automatically when opening a dedicated QGIS project. The macro processes all TIFF files located in the directory defined by the GLTF_INPUT environment variable .

 

Lastly, when importing GIS data into Unreal Engine and converting it to a format compatible with the engine, there are concerns regarding the potential impact on data accuracy and resolution. Therefore, a more detailed description of the converted format and its characteristics is deemed necessary.

The glTF format what we choose is highly efficient and versatile, making it ideal for various 3D applications like web-based experiences, AR/VR, and gaming. It's widely supported across platforms, ensuring seamless exchange of assets between different workflows. With its support for modern features and web technologies, glTF enables immersive experiences directly within web browsers, without plugins. Its status as an open standard ensures stability and ongoing development, making it a top choice for 3D content creation and distribution.

 

Added to the text

 

Author Response File: Author Response.docx