Uni-RS: A Spatially Faithful Unified Understanding and Generation Model for Remote Sensing
Authors: Weiyu Zhang, Yuan Hu, Yong Li, Yu Liu
Organizations: Institute of Remote Sensing and Geographic Information System, School of Earth and Space Sciences, Peking University, Beijing, 100871, China · Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong
Unified remote sensing multimodal models exhibit a pronounced spatial reversal curse: Although they can accurately recognize and describe object locations in images, they often fail to faithfully execute the same spatial relations during text-to-image generation, where such relations constitute core semantic information in remote sensing. Motivated by this observation, we propose Uni-RS, the first unified multimodal model tailored for remote sensing, to explicitly address the spatial asymmetry between understanding and generation. Specifically, we first introduce explicit Spatial-Layout Planning to transform textual instructions into spatial layout plans, decoupling geometric planning from visual synthesis. We then impose Spatial-Aware Query Supervision to bias learnable queries toward spatial relations explicitly specified in the instruction. Finally, we develop Image-Caption Spatial Layout Variation to expose the model to systematic geometry-consistent spatial transformations. Extensive experiments across multiple benchmarks show that our approach substantially improves spatial faithfulness in text-to-image generation, while maintaining strong performance on multimodal understanding tasks like image captioning, visual grounding, and VQA tasks.
Figures & tables
Figure 1: Illustration of the Spatial Reversal Curse in unified remote sensing multimodal models. While the model correctly describes spatial relations from an input image (left), it often fails to faithfully execute the same relations during text-to-image generation (right).
Figure 2: Quantitative characterization of the Spatial Reversal Curse. The baseline MetaQuery* model exhibits a pronounced gap between spatial understanding and spatially faithful text-to-image generation. The * denotes that the model was trained by us under the same experimental settings as described in Section 5.1 due to the absence of public checkpoints. The Uni-RS largely reduces this gap after incorporating the proposed spatial mechanisms.
Figure 3: Overview of the Uni-RS framework. Uni-RS integrates a multimodal large language model (MLLM) with a diffusion-based image generator through learnable queries and a Transformer-based connector. During training, the framework is further enhanced by Spatial-Layout Planning, Spatial-Aware Query Supervision, and Image–Caption Spatial Layout Variation, which jointly reinforce instruction-level spatial constraints and improve spatial faithfulness during generation.
Method
FID ( ↓ )
Zero-Shot Cls-OA ( ↑ )
CLIP ( ↑ )
Attn-GAN
95.81
32.56%
20.19
DAE-GAN
93.15
29.74%
19.69
DF-GAN
109.41
51.99%
19.76
Lafite
74.11
49.37%
22.52
DALL-E
191.93
28.59%
20.13
Txt2Img-MHN VQVAE
175.36
41.46%
21.35
Table 1: Comparison with existing text-to-image generation methods on RSICD. † indicates methods evaluated without fine-tuning on RSICD. See supplementary materials for detailed descriptions of baselines.
RSIEval
VRSBench
Method
FID ( ↓ )
SFR ( ↑ )
CLIP ( ↑ )
FID ( ↓ )
CLIP ( ↑ )
Text2Earth †
17.07
63.40
23.74
8.28
24.85
Text2Earth
16.22
65.10
23.79
7.42
24.93
Uni-RS (Ours)
13.04
80.16
24.01
4.51
25.46
Table 2: Comparison of spatial fidelity and generation quality on RSIEval and VRSBench. † indicates methods evaluated without fine-tuning on the corresponding dataset.
Table 3: Unified comparison on RSIEval and VRSBench-val across multimodal understanding tasks. † indicates methods evaluated without task-specific fine-tuning.
Figure 4: Qualitative comparison of spatial faithfulness in text-to-image generation. BLIP3-o Chen et al. (2025a) is a general-domain unified multimodal model for understanding and generation, while CRS-Diff Tang et al. (2024) and Text2Earth Liu et al. (2025a) are remote-sensing-specific text-to-image generation models. The Text2Earth model is fine-tuned using RSICap and VRSBench datasets to produce 512×512 images.
VRSBench
RSIEval
Method
FID
CLIP
FID
CLIP
SFR
Base
4.91
25.33
13.47
23.70
47.62
Base + SLP
4.62
25.40
13.44
23.81
54.00
Base + SLP + SQS
4.64
25.42
13.33
23.79
63.49
Base + SLP + SQS + ISV
4.51
25.46
13.04
24.01
80.16
Table 4: Ablation study on VRSBench and RSIEval. Components are added cumulatively: (1) Spatial-Layout Planning (SLP), (2) Spatial-Aware Query Supervision (SQS), (3) Image–Caption Spatial Layout Variation (ISV).
Practical remote sensing applications often require both understanding and generation capabilities for the same geographic scene. However, most existing methods address either understanding or generation in isolation, while existing unified remote sensing models' generative ability is limited to text-to-image. To bridge this gap, we propose Omni-RS, a unified framework supporting four remote sensing understanding tasks and five generation tasks. Specifically, we introduce the "Scene-Guided Two-Stage Training" strategy, which first adapts a multimodal large language model to remote sensing understanding and then uses its hidden states to guide a diffusion transformer for image generation. To enable joint learning across diverse generation tasks, we construct UniGen, a unified multi-task generation dataset, by organizing heterogeneous remote sensing data into a unified format. Furthermore, we introduce "Detailed Visual Conditioning", which uses visual conditions encoded by a VAE to guide the generation process, thereby supporting additional generation tasks that require reference images. Extensive experiments demonstrate that Omni-RS performs exceptionally well in understanding tasks and has achieved outstanding results in a variety of generative tasks.
Multimodal remote sensing image generation emerges as a promising paradigm for recovering complete and complementary observations from heterogeneous and partially observed remote sensing data. However, existing methods predominantly depend on sensor-specific fine-tuning of natural image generation models, limiting unified multimodal generation capacity due to the absence of shared representations and robust conditioning mechanisms. To address these challenges, we propose OmniRSI, a unified multimodal remote sensing image generation model. Specifically, we develop a remote sensing-specific variational autoencoder that captures multimodal priors and promotes a locally smooth latent space for unified representation and robust reconstruction across diverse observed data. Building upon that, we fully adapt Stable Diffusion 3.5 with a ControlNet branch to support unified multimodal generation and translation conditioned on textual and visual cues. Besides, we devise a training-free cyclic latent alignment mechanism that iteratively enriches incomplete visual conditions with generated multimodal information, progressively improving guidance reliability while preserving observed measurements. We also construct RSI-MM, a large-scale dataset comprising 11.5M multi-resolution images with text annotations and partially paired data for training and evaluation. Extensive experiments verify that OmniRSI achieves superior performance in multimodal reconstruction, generation and translation.
Remote sensing world models aim to both explain observed changes and forecast plausible futures, two tasks that share spatiotemporal priors. Existing methods, however, typically address them separately, limiting cross-task transfer. We present RS-WorldModel, a unified world model for remote sensing that jointly handles spatiotemporal change understanding and text-guided future scene forecasting, and we build RSWBench-1.1M, a 1.1 million sample dataset with rich language annotations covering both tasks. RS-WorldModel is trained in three stages: (1) Geo-Aware Generative Pre-training (GAGP) conditions forecasting on geographic and acquisition metadata; (2) synergistic instruction tuning (SIT) jointly trains understanding and forecasting; (3) verifiable reinforcement optimization (VRO) refines outputs with verifiable, task-specific rewards. With only 2B parameters, RS-WorldModel surpasses open-source models up to 120× larger on most spatiotemporal change question-answering metrics. It achieves an FID of 43.13 on text-guided future scene forecasting, outperforming all open-source baselines as well as the closed-source Gemini-2.5-Flash Image (Nano Banana).
Linrui Xu, Zhongan Wang, Fei Shen +4
Central South University · Zhejiang University · National University of Singapore +2